diff --git a/README.md b/README.md
index 784098aed..3048b8324 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# lodash-es v4.14.2
+# lodash-es v4.15.0
 
 The [Lodash](https://lodash.com/) library exported as [ES](http://www.ecma-international.org/ecma-262/6.0/) modules.
 
@@ -7,4 +7,4 @@ Generated using [lodash-cli](https://www.npmjs.com/package/lodash-cli):
 $ lodash modularize exports=es -o ./
 ```
 
-See the [package source](https://github.com/lodash/lodash/tree/4.14.2-es) for more details.
+See the [package source](https://github.com/lodash/lodash/tree/4.15.0-es) for more details.
diff --git a/_arrayIncludes.js b/_arrayIncludes.js
index a3dfdf9d1..12b48843f 100644
--- a/_arrayIncludes.js
+++ b/_arrayIncludes.js
@@ -5,7 +5,7 @@ import baseIndexOf from './_baseIndexOf.js';
  * specifying an index to search from.
  *
  * @private
- * @param {Array} [array] The array to search.
+ * @param {Array} [array] The array to inspect.
  * @param {*} target The value to search for.
  * @returns {boolean} Returns `true` if `target` is found, else `false`.
  */
diff --git a/_arrayIncludesWith.js b/_arrayIncludesWith.js
index 24edf9fcf..817ab7613 100644
--- a/_arrayIncludesWith.js
+++ b/_arrayIncludesWith.js
@@ -2,7 +2,7 @@
  * This function is like `arrayIncludes` except that it accepts a comparator.
  *
  * @private
- * @param {Array} [array] The array to search.
+ * @param {Array} [array] The array to inspect.
  * @param {*} target The value to search for.
  * @param {Function} comparator The comparator invoked per element.
  * @returns {boolean} Returns `true` if `target` is found, else `false`.
diff --git a/_arrayLikeKeys.js b/_arrayLikeKeys.js
index 16759b205..387113d19 100644
--- a/_arrayLikeKeys.js
+++ b/_arrayLikeKeys.js
@@ -2,7 +2,6 @@ import baseTimes from './_baseTimes.js';
 import isArguments from './isArguments.js';
 import isArray from './isArray.js';
 import isIndex from './_isIndex.js';
-import isString from './isString.js';
 
 /** Used for built-in method references. */
 var objectProto = Object.prototype;
@@ -19,7 +18,9 @@ var hasOwnProperty = objectProto.hasOwnProperty;
  * @returns {Array} Returns the array of property names.
  */
 function arrayLikeKeys(value, inherited) {
-  var result = (isArray(value) || isString(value) || isArguments(value))
+  // Safari 8.1 makes `arguments.callee` enumerable in strict mode.
+  // Safari 9 makes `arguments.length` enumerable in strict mode.
+  var result = (isArray(value) || isArguments(value))
     ? baseTimes(value.length, String)
     : [];
 
diff --git a/_asciiSize.js b/_asciiSize.js
new file mode 100644
index 000000000..bbf4df436
--- /dev/null
+++ b/_asciiSize.js
@@ -0,0 +1,12 @@
+import baseProperty from './_baseProperty.js';
+
+/**
+ * Gets the size of an ASCII `string`.
+ *
+ * @private
+ * @param {string} string The string inspect.
+ * @returns {number} Returns the string size.
+ */
+var asciiSize = baseProperty('length');
+
+export default asciiSize;
diff --git a/_asciiToArray.js b/_asciiToArray.js
new file mode 100644
index 000000000..1ab7be69c
--- /dev/null
+++ b/_asciiToArray.js
@@ -0,0 +1,12 @@
+/**
+ * Converts an ASCII `string` to an array.
+ *
+ * @private
+ * @param {string} string The string to convert.
+ * @returns {Array} Returns the converted array.
+ */
+function asciiToArray(string) {
+  return string.split('');
+}
+
+export default asciiToArray;
diff --git a/_asciiWords.js b/_asciiWords.js
new file mode 100644
index 000000000..7840636ba
--- /dev/null
+++ b/_asciiWords.js
@@ -0,0 +1,15 @@
+/** Used to match words composed of alphanumeric characters. */
+var reAsciiWord = /[^\x00-\x2f\x3a-\x40\x5b-\x60\x7b-\x7f]+/g;
+
+/**
+ * Splits an ASCII `string` into an array of its words.
+ *
+ * @private
+ * @param {string} The string to inspect.
+ * @returns {Array} Returns the words of `string`.
+ */
+function asciiWords(string) {
+  return string.match(reAsciiWord) || [];
+}
+
+export default asciiWords;
diff --git a/_assocIndexOf.js b/_assocIndexOf.js
index d4985ce1f..88afb3979 100644
--- a/_assocIndexOf.js
+++ b/_assocIndexOf.js
@@ -4,7 +4,7 @@ import eq from './eq.js';
  * Gets the index at which the `key` is found in `array` of key-value pairs.
  *
  * @private
- * @param {Array} array The array to search.
+ * @param {Array} array The array to inspect.
  * @param {*} key The key to search for.
  * @returns {number} Returns the index of the matched value, else `-1`.
  */
diff --git a/_baseFindIndex.js b/_baseFindIndex.js
index 0295f7d96..860636ee5 100644
--- a/_baseFindIndex.js
+++ b/_baseFindIndex.js
@@ -3,7 +3,7 @@
  * support for iteratee shorthands.
  *
  * @private
- * @param {Array} array The array to search.
+ * @param {Array} array The array to inspect.
  * @param {Function} predicate The function invoked per iteration.
  * @param {number} fromIndex The index to search from.
  * @param {boolean} [fromRight] Specify iterating from right to left.
diff --git a/_baseFindKey.js b/_baseFindKey.js
index 816e74374..6d1932eed 100644
--- a/_baseFindKey.js
+++ b/_baseFindKey.js
@@ -4,7 +4,7 @@
  * using `eachFunc`.
  *
  * @private
- * @param {Array|Object} collection The collection to search.
+ * @param {Array|Object} collection The collection to inspect.
  * @param {Function} predicate The function invoked per iteration.
  * @param {Function} eachFunc The function to iterate over `collection`.
  * @returns {*} Returns the found element or its key, else `undefined`.
diff --git a/_baseIndexOf.js b/_baseIndexOf.js
index 9152c3edc..69a5c3b21 100644
--- a/_baseIndexOf.js
+++ b/_baseIndexOf.js
@@ -5,7 +5,7 @@ import baseIsNaN from './_baseIsNaN.js';
  * The base implementation of `_.indexOf` without `fromIndex` bounds checks.
  *
  * @private
- * @param {Array} array The array to search.
+ * @param {Array} array The array to inspect.
  * @param {*} value The value to search for.
  * @param {number} fromIndex The index to search from.
  * @returns {number} Returns the index of the matched value, else `-1`.
diff --git a/_baseIndexOfWith.js b/_baseIndexOfWith.js
index 028ad9159..38831b26b 100644
--- a/_baseIndexOfWith.js
+++ b/_baseIndexOfWith.js
@@ -2,7 +2,7 @@
  * This function is like `baseIndexOf` except that it accepts a comparator.
  *
  * @private
- * @param {Array} array The array to search.
+ * @param {Array} array The array to inspect.
  * @param {*} value The value to search for.
  * @param {number} fromIndex The index to search from.
  * @param {Function} comparator The comparator invoked per element.
diff --git a/_baseIsNative.js b/_baseIsNative.js
index d41a99c5b..8e38ee54b 100644
--- a/_baseIsNative.js
+++ b/_baseIsNative.js
@@ -14,10 +14,11 @@ var reRegExpChar = /[\\^$.*+?()[\]{}|]/g;
 var reIsHostCtor = /^\[object .+?Constructor\]$/;
 
 /** Used for built-in method references. */
-var objectProto = Object.prototype;
+var funcProto = Function.prototype,
+    objectProto = Object.prototype;
 
 /** Used to resolve the decompiled source of functions. */
-var funcToString = Function.prototype.toString;
+var funcToString = funcProto.toString;
 
 /** Used to check objects for own properties. */
 var hasOwnProperty = objectProto.hasOwnProperty;
diff --git a/_baseSet.js b/_baseSet.js
index e19e989be..187b3e5c2 100644
--- a/_baseSet.js
+++ b/_baseSet.js
@@ -9,7 +9,7 @@ import toKey from './_toKey.js';
  * The base implementation of `_.set`.
  *
  * @private
- * @param {Object} object The object to query.
+ * @param {Object} object The object to modify.
  * @param {Array|string} path The path of the property to set.
  * @param {*} value The value to set.
  * @param {Function} [customizer] The function to customize path creation.
diff --git a/_baseUpdate.js b/_baseUpdate.js
index 8bf7d1d11..70dd150f4 100644
--- a/_baseUpdate.js
+++ b/_baseUpdate.js
@@ -5,7 +5,7 @@ import baseSet from './_baseSet.js';
  * The base implementation of `_.update`.
  *
  * @private
- * @param {Object} object The object to query.
+ * @param {Object} object The object to modify.
  * @param {Array|string} path The path of the property to update.
  * @param {Function} updater The function to produce the updated value.
  * @param {Function} [customizer] The function to customize path creation.
diff --git a/_createCaseFirst.js b/_createCaseFirst.js
index f569ce8c7..333c7c4c0 100644
--- a/_createCaseFirst.js
+++ b/_createCaseFirst.js
@@ -1,5 +1,5 @@
 import castSlice from './_castSlice.js';
-import reHasComplexSymbol from './_reHasComplexSymbol.js';
+import hasUnicode from './_hasUnicode.js';
 import stringToArray from './_stringToArray.js';
 import toString from './toString.js';
 
@@ -14,7 +14,7 @@ function createCaseFirst(methodName) {
   return function(string) {
     string = toString(string);
 
-    var strSymbols = reHasComplexSymbol.test(string)
+    var strSymbols = hasUnicode(string)
       ? stringToArray(string)
       : undefined;
 
diff --git a/_createPadding.js b/_createPadding.js
index b1653992f..1e35cd82b 100644
--- a/_createPadding.js
+++ b/_createPadding.js
@@ -1,7 +1,7 @@
 import baseRepeat from './_baseRepeat.js';
 import baseToString from './_baseToString.js';
 import castSlice from './_castSlice.js';
-import reHasComplexSymbol from './_reHasComplexSymbol.js';
+import hasUnicode from './_hasUnicode.js';
 import stringSize from './_stringSize.js';
 import stringToArray from './_stringToArray.js';
 
@@ -25,7 +25,7 @@ function createPadding(length, chars) {
     return charsLength ? baseRepeat(chars, length) : chars;
   }
   var result = baseRepeat(chars, nativeCeil(length / stringSize(chars)));
-  return reHasComplexSymbol.test(chars)
+  return hasUnicode(chars)
     ? castSlice(stringToArray(result), 0, length).join('')
     : result.slice(0, length);
 }
diff --git a/_deburrLetter.js b/_deburrLetter.js
index fe6a3ab90..896d14c50 100644
--- a/_deburrLetter.js
+++ b/_deburrLetter.js
@@ -1,15 +1,16 @@
 import basePropertyOf from './_basePropertyOf.js';
 
-/** Used to map latin-1 supplementary letters to basic latin letters. */
+/** Used to map Latin Unicode letters to basic Latin letters. */
 var deburredLetters = {
+  // Latin-1 Supplement block.
   '\xc0': 'A',  '\xc1': 'A', '\xc2': 'A', '\xc3': 'A', '\xc4': 'A', '\xc5': 'A',
   '\xe0': 'a',  '\xe1': 'a', '\xe2': 'a', '\xe3': 'a', '\xe4': 'a', '\xe5': 'a',
   '\xc7': 'C',  '\xe7': 'c',
   '\xd0': 'D',  '\xf0': 'd',
   '\xc8': 'E',  '\xc9': 'E', '\xca': 'E', '\xcb': 'E',
   '\xe8': 'e',  '\xe9': 'e', '\xea': 'e', '\xeb': 'e',
-  '\xcC': 'I',  '\xcd': 'I', '\xce': 'I', '\xcf': 'I',
-  '\xeC': 'i',  '\xed': 'i', '\xee': 'i', '\xef': 'i',
+  '\xcc': 'I',  '\xcd': 'I', '\xce': 'I', '\xcf': 'I',
+  '\xec': 'i',  '\xed': 'i', '\xee': 'i', '\xef': 'i',
   '\xd1': 'N',  '\xf1': 'n',
   '\xd2': 'O',  '\xd3': 'O', '\xd4': 'O', '\xd5': 'O', '\xd6': 'O', '\xd8': 'O',
   '\xf2': 'o',  '\xf3': 'o', '\xf4': 'o', '\xf5': 'o', '\xf6': 'o', '\xf8': 'o',
@@ -18,11 +19,48 @@ var deburredLetters = {
   '\xdd': 'Y',  '\xfd': 'y', '\xff': 'y',
   '\xc6': 'Ae', '\xe6': 'ae',
   '\xde': 'Th', '\xfe': 'th',
-  '\xdf': 'ss'
+  '\xdf': 'ss',
+  // Latin Extended-A block.
+  '\u0100': 'A',  '\u0102': 'A', '\u0104': 'A',
+  '\u0101': 'a',  '\u0103': 'a', '\u0105': 'a',
+  '\u0106': 'C',  '\u0108': 'C', '\u010a': 'C', '\u010c': 'C',
+  '\u0107': 'c',  '\u0109': 'c', '\u010b': 'c', '\u010d': 'c',
+  '\u010e': 'D',  '\u0110': 'D', '\u010f': 'd', '\u0111': 'd',
+  '\u0112': 'E',  '\u0114': 'E', '\u0116': 'E', '\u0118': 'E', '\u011a': 'E',
+  '\u0113': 'e',  '\u0115': 'e', '\u0117': 'e', '\u0119': 'e', '\u011b': 'e',
+  '\u011c': 'G',  '\u011e': 'G', '\u0120': 'G', '\u0122': 'G',
+  '\u011d': 'g',  '\u011f': 'g', '\u0121': 'g', '\u0123': 'g',
+  '\u0124': 'H',  '\u0126': 'H', '\u0125': 'h', '\u0127': 'h',
+  '\u0128': 'I',  '\u012a': 'I', '\u012c': 'I', '\u012e': 'I', '\u0130': 'I',
+  '\u0129': 'i',  '\u012b': 'i', '\u012d': 'i', '\u012f': 'i', '\u0131': 'i',
+  '\u0134': 'J',  '\u0135': 'j',
+  '\u0136': 'K',  '\u0137': 'k', '\u0138': 'k',
+  '\u0139': 'L',  '\u013b': 'L', '\u013d': 'L', '\u013f': 'L', '\u0141': 'L',
+  '\u013a': 'l',  '\u013c': 'l', '\u013e': 'l', '\u0140': 'l', '\u0142': 'l',
+  '\u0143': 'N',  '\u0145': 'N', '\u0147': 'N', '\u014a': 'N',
+  '\u0144': 'n',  '\u0146': 'n', '\u0148': 'n', '\u014b': 'n',
+  '\u014c': 'O',  '\u014e': 'O', '\u0150': 'O',
+  '\u014d': 'o',  '\u014f': 'o', '\u0151': 'o',
+  '\u0154': 'R',  '\u0156': 'R', '\u0158': 'R',
+  '\u0155': 'r',  '\u0157': 'r', '\u0159': 'r',
+  '\u015a': 'S',  '\u015c': 'S', '\u015e': 'S', '\u0160': 'S',
+  '\u015b': 's',  '\u015d': 's', '\u015f': 's', '\u0161': 's',
+  '\u0162': 'T',  '\u0164': 'T', '\u0166': 'T',
+  '\u0163': 't',  '\u0165': 't', '\u0167': 't',
+  '\u0168': 'U',  '\u016a': 'U', '\u016c': 'U', '\u016e': 'U', '\u0170': 'U', '\u0172': 'U',
+  '\u0169': 'u',  '\u016b': 'u', '\u016d': 'u', '\u016f': 'u', '\u0171': 'u', '\u0173': 'u',
+  '\u0174': 'W',  '\u0175': 'w',
+  '\u0176': 'Y',  '\u0177': 'y', '\u0178': 'Y',
+  '\u0179': 'Z',  '\u017b': 'Z', '\u017d': 'Z',
+  '\u017a': 'z',  '\u017c': 'z', '\u017e': 'z',
+  '\u0132': 'IJ', '\u0133': 'ij',
+  '\u0152': 'Oe', '\u0153': 'oe',
+  '\u0149': "'n", '\u017f': 'ss'
 };
 
 /**
- * Used by `_.deburr` to convert latin-1 supplementary letters to basic latin letters.
+ * Used by `_.deburr` to convert Latin-1 Supplement and Latin Extended-A
+ * letters to basic Latin letters.
  *
  * @private
  * @param {string} letter The matched letter to deburr.
diff --git a/_getTag.js b/_getTag.js
index 3fdc421c5..d2c415613 100644
--- a/_getTag.js
+++ b/_getTag.js
@@ -42,7 +42,7 @@ var dataViewCtorString = toSource(DataView),
 var getTag = baseGetTag;
 
 // Fallback for data views, maps, sets, and weak maps in IE 11,
-// for data views in Edge, and promises in Node.js.
+// for data views in Edge < 14, and promises in Node.js.
 if ((DataView && getTag(new DataView(new ArrayBuffer(1))) != dataViewTag) ||
     (Map && getTag(new Map) != mapTag) ||
     (Promise && getTag(Promise.resolve()) != promiseTag) ||
diff --git a/_hasPath.js b/_hasPath.js
index 669355eb4..019cf4135 100644
--- a/_hasPath.js
+++ b/_hasPath.js
@@ -4,7 +4,6 @@ import isArray from './isArray.js';
 import isIndex from './_isIndex.js';
 import isKey from './_isKey.js';
 import isLength from './isLength.js';
-import isString from './isString.js';
 import toKey from './_toKey.js';
 
 /**
@@ -35,7 +34,7 @@ function hasPath(object, path, hasFunc) {
   }
   var length = object ? object.length : 0;
   return !!length && isLength(length) && isIndex(key, length) &&
-    (isArray(object) || isString(object) || isArguments(object));
+    (isArray(object) || isArguments(object));
 }
 
 export default hasPath;
diff --git a/_reHasComplexSymbol.js b/_hasUnicode.js
similarity index 52%
rename from _reHasComplexSymbol.js
rename to _hasUnicode.js
index fff4f9cbb..ae9548690 100644
--- a/_reHasComplexSymbol.js
+++ b/_hasUnicode.js
@@ -8,6 +8,17 @@ var rsAstralRange = '\\ud800-\\udfff',
 var rsZWJ = '\\u200d';
 
 /** Used to detect strings with [zero-width joiners or code points from the astral planes](http://eev.ee/blog/2015/09/12/dark-corners-of-unicode/). */
-var reHasComplexSymbol = RegExp('[' + rsZWJ + rsAstralRange  + rsComboMarksRange + rsComboSymbolsRange + rsVarRange + ']');
+var reHasUnicode = RegExp('[' + rsZWJ + rsAstralRange  + rsComboMarksRange + rsComboSymbolsRange + rsVarRange + ']');
 
-export default reHasComplexSymbol;
+/**
+ * Checks if `string` contains Unicode symbols.
+ *
+ * @private
+ * @param {string} string The string to inspect.
+ * @returns {boolean} Returns `true` if a symbol is found, else `false`.
+ */
+function hasUnicode(string) {
+  return reHasUnicode.test(string);
+}
+
+export default hasUnicode;
diff --git a/_hasUnicodeWord.js b/_hasUnicodeWord.js
new file mode 100644
index 000000000..b2a026093
--- /dev/null
+++ b/_hasUnicodeWord.js
@@ -0,0 +1,15 @@
+/** Used to detect strings that need a more robust regexp to match words. */
+var reHasUnicodeWord = /[a-z][A-Z]|[A-Z]{2,}[a-z]|[0-9][a-zA-Z]|[a-zA-Z][0-9]|[^a-zA-Z0-9 ]/;
+
+/**
+ * Checks if `string` contains a word composed of Unicode symbols.
+ *
+ * @private
+ * @param {string} string The string to inspect.
+ * @returns {boolean} Returns `true` if a word is found, else `false`.
+ */
+function hasUnicodeWord(string) {
+  return reHasUnicodeWord.test(string);
+}
+
+export default hasUnicodeWord;
diff --git a/_stringSize.js b/_stringSize.js
index 1109286ae..17443a8d1 100644
--- a/_stringSize.js
+++ b/_stringSize.js
@@ -1,30 +1,6 @@
-import reHasComplexSymbol from './_reHasComplexSymbol.js';
-
-/** Used to compose unicode character classes. */
-var rsAstralRange = '\\ud800-\\udfff',
-    rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
-    rsComboSymbolsRange = '\\u20d0-\\u20f0',
-    rsVarRange = '\\ufe0e\\ufe0f';
-
-/** Used to compose unicode capture groups. */
-var rsAstral = '[' + rsAstralRange + ']',
-    rsCombo = '[' + rsComboMarksRange + rsComboSymbolsRange + ']',
-    rsFitz = '\\ud83c[\\udffb-\\udfff]',
-    rsModifier = '(?:' + rsCombo + '|' + rsFitz + ')',
-    rsNonAstral = '[^' + rsAstralRange + ']',
-    rsRegional = '(?:\\ud83c[\\udde6-\\uddff]){2}',
-    rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]',
-    rsZWJ = '\\u200d';
-
-/** Used to compose unicode regexes. */
-var reOptMod = rsModifier + '?',
-    rsOptVar = '[' + rsVarRange + ']?',
-    rsOptJoin = '(?:' + rsZWJ + '(?:' + [rsNonAstral, rsRegional, rsSurrPair].join('|') + ')' + rsOptVar + reOptMod + ')*',
-    rsSeq = rsOptVar + reOptMod + rsOptJoin,
-    rsSymbol = '(?:' + [rsNonAstral + rsCombo + '?', rsCombo, rsRegional, rsSurrPair, rsAstral].join('|') + ')';
-
-/** Used to match [string symbols](https://mathiasbynens.be/notes/javascript-unicode). */
-var reComplexSymbol = RegExp(rsFitz + '(?=' + rsFitz + ')|' + rsSymbol + rsSeq, 'g');
+import asciiSize from './_asciiSize.js';
+import hasUnicode from './_hasUnicode.js';
+import unicodeSize from './_unicodeSize.js';
 
 /**
  * Gets the number of symbols in `string`.
@@ -34,14 +10,9 @@ var reComplexSymbol = RegExp(rsFitz + '(?=' + rsFitz + ')|' + rsSymbol + rsSeq,
  * @returns {number} Returns the string size.
  */
 function stringSize(string) {
-  if (!(string && reHasComplexSymbol.test(string))) {
-    return string.length;
-  }
-  var result = reComplexSymbol.lastIndex = 0;
-  while (reComplexSymbol.test(string)) {
-    result++;
-  }
-  return result;
+  return hasUnicode(string)
+    ? unicodeSize(string)
+    : asciiSize(string);
 }
 
 export default stringSize;
diff --git a/_stringToArray.js b/_stringToArray.js
index 136909b3c..1ce84fd4e 100644
--- a/_stringToArray.js
+++ b/_stringToArray.js
@@ -1,28 +1,6 @@
-/** Used to compose unicode character classes. */
-var rsAstralRange = '\\ud800-\\udfff',
-    rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
-    rsComboSymbolsRange = '\\u20d0-\\u20f0',
-    rsVarRange = '\\ufe0e\\ufe0f';
-
-/** Used to compose unicode capture groups. */
-var rsAstral = '[' + rsAstralRange + ']',
-    rsCombo = '[' + rsComboMarksRange + rsComboSymbolsRange + ']',
-    rsFitz = '\\ud83c[\\udffb-\\udfff]',
-    rsModifier = '(?:' + rsCombo + '|' + rsFitz + ')',
-    rsNonAstral = '[^' + rsAstralRange + ']',
-    rsRegional = '(?:\\ud83c[\\udde6-\\uddff]){2}',
-    rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]',
-    rsZWJ = '\\u200d';
-
-/** Used to compose unicode regexes. */
-var reOptMod = rsModifier + '?',
-    rsOptVar = '[' + rsVarRange + ']?',
-    rsOptJoin = '(?:' + rsZWJ + '(?:' + [rsNonAstral, rsRegional, rsSurrPair].join('|') + ')' + rsOptVar + reOptMod + ')*',
-    rsSeq = rsOptVar + reOptMod + rsOptJoin,
-    rsSymbol = '(?:' + [rsNonAstral + rsCombo + '?', rsCombo, rsRegional, rsSurrPair, rsAstral].join('|') + ')';
-
-/** Used to match [string symbols](https://mathiasbynens.be/notes/javascript-unicode). */
-var reComplexSymbol = RegExp(rsFitz + '(?=' + rsFitz + ')|' + rsSymbol + rsSeq, 'g');
+import asciiToArray from './_asciiToArray.js';
+import hasUnicode from './_hasUnicode.js';
+import unicodeToArray from './_unicodeToArray.js';
 
 /**
  * Converts `string` to an array.
@@ -32,7 +10,9 @@ var reComplexSymbol = RegExp(rsFitz + '(?=' + rsFitz + ')|' + rsSymbol + rsSeq,
  * @returns {Array} Returns the converted array.
  */
 function stringToArray(string) {
-  return string.match(reComplexSymbol);
+  return hasUnicode(string)
+    ? unicodeToArray(string)
+    : asciiToArray(string);
 }
 
 export default stringToArray;
diff --git a/_toSource.js b/_toSource.js
index 04d5b5072..2a7f05f1f 100644
--- a/_toSource.js
+++ b/_toSource.js
@@ -1,5 +1,8 @@
+/** Used for built-in method references. */
+var funcProto = Function.prototype;
+
 /** Used to resolve the decompiled source of functions. */
-var funcToString = Function.prototype.toString;
+var funcToString = funcProto.toString;
 
 /**
  * Converts `func` to its source code.
diff --git a/_unicodeSize.js b/_unicodeSize.js
new file mode 100644
index 000000000..83117b0db
--- /dev/null
+++ b/_unicodeSize.js
@@ -0,0 +1,42 @@
+/** Used to compose unicode character classes. */
+var rsAstralRange = '\\ud800-\\udfff',
+    rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
+    rsComboSymbolsRange = '\\u20d0-\\u20f0',
+    rsVarRange = '\\ufe0e\\ufe0f';
+
+/** Used to compose unicode capture groups. */
+var rsAstral = '[' + rsAstralRange + ']',
+    rsCombo = '[' + rsComboMarksRange + rsComboSymbolsRange + ']',
+    rsFitz = '\\ud83c[\\udffb-\\udfff]',
+    rsModifier = '(?:' + rsCombo + '|' + rsFitz + ')',
+    rsNonAstral = '[^' + rsAstralRange + ']',
+    rsRegional = '(?:\\ud83c[\\udde6-\\uddff]){2}',
+    rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]',
+    rsZWJ = '\\u200d';
+
+/** Used to compose unicode regexes. */
+var reOptMod = rsModifier + '?',
+    rsOptVar = '[' + rsVarRange + ']?',
+    rsOptJoin = '(?:' + rsZWJ + '(?:' + [rsNonAstral, rsRegional, rsSurrPair].join('|') + ')' + rsOptVar + reOptMod + ')*',
+    rsSeq = rsOptVar + reOptMod + rsOptJoin,
+    rsSymbol = '(?:' + [rsNonAstral + rsCombo + '?', rsCombo, rsRegional, rsSurrPair, rsAstral].join('|') + ')';
+
+/** Used to match [string symbols](https://mathiasbynens.be/notes/javascript-unicode). */
+var reUnicode = RegExp(rsFitz + '(?=' + rsFitz + ')|' + rsSymbol + rsSeq, 'g');
+
+/**
+ * Gets the size of a Unicode `string`.
+ *
+ * @private
+ * @param {string} string The string inspect.
+ * @returns {number} Returns the string size.
+ */
+function unicodeSize(string) {
+  var result = reUnicode.lastIndex = 0;
+  while (reUnicode.test(string)) {
+    result++;
+  }
+  return result;
+}
+
+export default unicodeSize;
diff --git a/_unicodeToArray.js b/_unicodeToArray.js
new file mode 100644
index 000000000..0ef8e3e4d
--- /dev/null
+++ b/_unicodeToArray.js
@@ -0,0 +1,38 @@
+/** Used to compose unicode character classes. */
+var rsAstralRange = '\\ud800-\\udfff',
+    rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
+    rsComboSymbolsRange = '\\u20d0-\\u20f0',
+    rsVarRange = '\\ufe0e\\ufe0f';
+
+/** Used to compose unicode capture groups. */
+var rsAstral = '[' + rsAstralRange + ']',
+    rsCombo = '[' + rsComboMarksRange + rsComboSymbolsRange + ']',
+    rsFitz = '\\ud83c[\\udffb-\\udfff]',
+    rsModifier = '(?:' + rsCombo + '|' + rsFitz + ')',
+    rsNonAstral = '[^' + rsAstralRange + ']',
+    rsRegional = '(?:\\ud83c[\\udde6-\\uddff]){2}',
+    rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]',
+    rsZWJ = '\\u200d';
+
+/** Used to compose unicode regexes. */
+var reOptMod = rsModifier + '?',
+    rsOptVar = '[' + rsVarRange + ']?',
+    rsOptJoin = '(?:' + rsZWJ + '(?:' + [rsNonAstral, rsRegional, rsSurrPair].join('|') + ')' + rsOptVar + reOptMod + ')*',
+    rsSeq = rsOptVar + reOptMod + rsOptJoin,
+    rsSymbol = '(?:' + [rsNonAstral + rsCombo + '?', rsCombo, rsRegional, rsSurrPair, rsAstral].join('|') + ')';
+
+/** Used to match [string symbols](https://mathiasbynens.be/notes/javascript-unicode). */
+var reUnicode = RegExp(rsFitz + '(?=' + rsFitz + ')|' + rsSymbol + rsSeq, 'g');
+
+/**
+ * Converts a Unicode `string` to an array.
+ *
+ * @private
+ * @param {string} string The string to convert.
+ * @returns {Array} Returns the converted array.
+ */
+function unicodeToArray(string) {
+  return string.match(reUnicode) || [];
+}
+
+export default unicodeToArray;
diff --git a/_unicodeWords.js b/_unicodeWords.js
new file mode 100644
index 000000000..9d605fe11
--- /dev/null
+++ b/_unicodeWords.js
@@ -0,0 +1,63 @@
+/** Used to compose unicode character classes. */
+var rsAstralRange = '\\ud800-\\udfff',
+    rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
+    rsComboSymbolsRange = '\\u20d0-\\u20f0',
+    rsDingbatRange = '\\u2700-\\u27bf',
+    rsLowerRange = 'a-z\\xdf-\\xf6\\xf8-\\xff',
+    rsMathOpRange = '\\xac\\xb1\\xd7\\xf7',
+    rsNonCharRange = '\\x00-\\x2f\\x3a-\\x40\\x5b-\\x60\\x7b-\\xbf',
+    rsPunctuationRange = '\\u2000-\\u206f',
+    rsSpaceRange = ' \\t\\x0b\\f\\xa0\\ufeff\\n\\r\\u2028\\u2029\\u1680\\u180e\\u2000\\u2001\\u2002\\u2003\\u2004\\u2005\\u2006\\u2007\\u2008\\u2009\\u200a\\u202f\\u205f\\u3000',
+    rsUpperRange = 'A-Z\\xc0-\\xd6\\xd8-\\xde',
+    rsVarRange = '\\ufe0e\\ufe0f',
+    rsBreakRange = rsMathOpRange + rsNonCharRange + rsPunctuationRange + rsSpaceRange;
+
+/** Used to compose unicode capture groups. */
+var rsApos = "['\u2019]",
+    rsBreak = '[' + rsBreakRange + ']',
+    rsCombo = '[' + rsComboMarksRange + rsComboSymbolsRange + ']',
+    rsDigits = '\\d+',
+    rsDingbat = '[' + rsDingbatRange + ']',
+    rsLower = '[' + rsLowerRange + ']',
+    rsMisc = '[^' + rsAstralRange + rsBreakRange + rsDigits + rsDingbatRange + rsLowerRange + rsUpperRange + ']',
+    rsFitz = '\\ud83c[\\udffb-\\udfff]',
+    rsModifier = '(?:' + rsCombo + '|' + rsFitz + ')',
+    rsNonAstral = '[^' + rsAstralRange + ']',
+    rsRegional = '(?:\\ud83c[\\udde6-\\uddff]){2}',
+    rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]',
+    rsUpper = '[' + rsUpperRange + ']',
+    rsZWJ = '\\u200d';
+
+/** Used to compose unicode regexes. */
+var rsLowerMisc = '(?:' + rsLower + '|' + rsMisc + ')',
+    rsUpperMisc = '(?:' + rsUpper + '|' + rsMisc + ')',
+    rsOptLowerContr = '(?:' + rsApos + '(?:d|ll|m|re|s|t|ve))?',
+    rsOptUpperContr = '(?:' + rsApos + '(?:D|LL|M|RE|S|T|VE))?',
+    reOptMod = rsModifier + '?',
+    rsOptVar = '[' + rsVarRange + ']?',
+    rsOptJoin = '(?:' + rsZWJ + '(?:' + [rsNonAstral, rsRegional, rsSurrPair].join('|') + ')' + rsOptVar + reOptMod + ')*',
+    rsSeq = rsOptVar + reOptMod + rsOptJoin,
+    rsEmoji = '(?:' + [rsDingbat, rsRegional, rsSurrPair].join('|') + ')' + rsSeq;
+
+/** Used to match complex or compound words. */
+var reUnicodeWord = RegExp([
+  rsUpper + '?' + rsLower + '+' + rsOptLowerContr + '(?=' + [rsBreak, rsUpper, '$'].join('|') + ')',
+  rsUpperMisc + '+' + rsOptUpperContr + '(?=' + [rsBreak, rsUpper + rsLowerMisc, '$'].join('|') + ')',
+  rsUpper + '?' + rsLowerMisc + '+' + rsOptLowerContr,
+  rsUpper + '+' + rsOptUpperContr,
+  rsDigits,
+  rsEmoji
+].join('|'), 'g');
+
+/**
+ * Splits a Unicode `string` into an array of its words.
+ *
+ * @private
+ * @param {string} The string to inspect.
+ * @returns {Array} Returns the words of `string`.
+ */
+function unicodeWords(string) {
+  return string.match(reUnicodeWord) || [];
+}
+
+export default unicodeWords;
diff --git a/deburr.js b/deburr.js
index 1d93de941..0fa630440 100644
--- a/deburr.js
+++ b/deburr.js
@@ -1,8 +1,8 @@
 import deburrLetter from './_deburrLetter.js';
 import toString from './toString.js';
 
-/** Used to match latin-1 supplementary letters (excluding mathematical operators). */
-var reLatin1 = /[\xc0-\xd6\xd8-\xde\xdf-\xf6\xf8-\xff]/g;
+/** Used to match Latin Unicode letters (excluding mathematical operators). */
+var reLatin = /[\xc0-\xd6\xd8-\xf6\xf8-\xff\u0100-\u017f]/g;
 
 /** Used to compose unicode character classes. */
 var rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
@@ -19,8 +19,9 @@ var reComboMark = RegExp(rsCombo, 'g');
 
 /**
  * Deburrs `string` by converting
- * [latin-1 supplementary letters](https://en.wikipedia.org/wiki/Latin-1_Supplement_(Unicode_block)#Character_table)
- * to basic latin letters and removing
+ * [Latin-1 Supplement](https://en.wikipedia.org/wiki/Latin-1_Supplement_(Unicode_block)#Character_table)
+ * and [Latin Extended-A](https://en.wikipedia.org/wiki/Latin_Extended-A)
+ * letters to basic Latin letters and removing
  * [combining diacritical marks](https://en.wikipedia.org/wiki/Combining_Diacritical_Marks).
  *
  * @static
@@ -36,7 +37,7 @@ var reComboMark = RegExp(rsCombo, 'g');
  */
 function deburr(string) {
   string = toString(string);
-  return string && string.replace(reLatin1, deburrLetter).replace(reComboMark, '');
+  return string && string.replace(reLatin, deburrLetter).replace(reComboMark, '');
 }
 
 export default deburr;
diff --git a/endsWith.js b/endsWith.js
index 65fe0a646..1554a6e40 100644
--- a/endsWith.js
+++ b/endsWith.js
@@ -10,7 +10,7 @@ import toString from './toString.js';
  * @memberOf _
  * @since 3.0.0
  * @category String
- * @param {string} [string=''] The string to search.
+ * @param {string} [string=''] The string to inspect.
  * @param {string} [target] The string to search for.
  * @param {number} [position=string.length] The position to search up to.
  * @returns {boolean} Returns `true` if `string` ends with `target`,
diff --git a/find.js b/find.js
index 7084c3f2d..24a792b56 100644
--- a/find.js
+++ b/find.js
@@ -10,7 +10,7 @@ import findIndex from './findIndex.js';
  * @memberOf _
  * @since 0.1.0
  * @category Collection
- * @param {Array|Object} collection The collection to search.
+ * @param {Array|Object} collection The collection to inspect.
  * @param {Function} [predicate=_.identity]
  *  The function invoked per iteration.
  * @param {number} [fromIndex=0] The index to search from.
diff --git a/findIndex.js b/findIndex.js
index b14022522..084f48af2 100644
--- a/findIndex.js
+++ b/findIndex.js
@@ -13,7 +13,7 @@ var nativeMax = Math.max;
  * @memberOf _
  * @since 1.1.0
  * @category Array
- * @param {Array} array The array to search.
+ * @param {Array} array The array to inspect.
  * @param {Function} [predicate=_.identity]
  *  The function invoked per iteration.
  * @param {number} [fromIndex=0] The index to search from.
diff --git a/findKey.js b/findKey.js
index 6e2519511..a578ede4e 100644
--- a/findKey.js
+++ b/findKey.js
@@ -10,7 +10,7 @@ import baseIteratee from './_baseIteratee.js';
  * @memberOf _
  * @since 1.1.0
  * @category Object
- * @param {Object} object The object to search.
+ * @param {Object} object The object to inspect.
  * @param {Function} [predicate=_.identity] The function invoked per iteration.
  * @returns {string|undefined} Returns the key of the matched element,
  *  else `undefined`.
diff --git a/findLast.js b/findLast.js
index d353213e7..236ed2624 100644
--- a/findLast.js
+++ b/findLast.js
@@ -9,7 +9,7 @@ import findLastIndex from './findLastIndex.js';
  * @memberOf _
  * @since 2.0.0
  * @category Collection
- * @param {Array|Object} collection The collection to search.
+ * @param {Array|Object} collection The collection to inspect.
  * @param {Function} [predicate=_.identity]
  *  The function invoked per iteration.
  * @param {number} [fromIndex=collection.length-1] The index to search from.
diff --git a/findLastIndex.js b/findLastIndex.js
index 3c39a6c07..1881ea16d 100644
--- a/findLastIndex.js
+++ b/findLastIndex.js
@@ -14,7 +14,7 @@ var nativeMax = Math.max,
  * @memberOf _
  * @since 2.0.0
  * @category Array
- * @param {Array} array The array to search.
+ * @param {Array} array The array to inspect.
  * @param {Function} [predicate=_.identity]
  *  The function invoked per iteration.
  * @param {number} [fromIndex=array.length-1] The index to search from.
diff --git a/findLastKey.js b/findLastKey.js
index 67c8b2893..6b391dc03 100644
--- a/findLastKey.js
+++ b/findLastKey.js
@@ -10,7 +10,7 @@ import baseIteratee from './_baseIteratee.js';
  * @memberOf _
  * @since 2.0.0
  * @category Object
- * @param {Object} object The object to search.
+ * @param {Object} object The object to inspect.
  * @param {Function} [predicate=_.identity] The function invoked per iteration.
  * @returns {string|undefined} Returns the key of the matched element,
  *  else `undefined`.
diff --git a/includes.js b/includes.js
index c438da7b4..7bb379384 100644
--- a/includes.js
+++ b/includes.js
@@ -18,7 +18,7 @@ var nativeMax = Math.max;
  * @memberOf _
  * @since 0.1.0
  * @category Collection
- * @param {Array|Object|string} collection The collection to search.
+ * @param {Array|Object|string} collection The collection to inspect.
  * @param {*} value The value to search for.
  * @param {number} [fromIndex=0] The index to search from.
  * @param- {Object} [guard] Enables use as an iteratee for methods like `_.reduce`.
diff --git a/indexOf.js b/indexOf.js
index 6e3adf803..7da26981b 100644
--- a/indexOf.js
+++ b/indexOf.js
@@ -14,7 +14,7 @@ var nativeMax = Math.max;
  * @memberOf _
  * @since 0.1.0
  * @category Array
- * @param {Array} array The array to search.
+ * @param {Array} array The array to inspect.
  * @param {*} value The value to search for.
  * @param {number} [fromIndex=0] The index to search from.
  * @returns {number} Returns the index of the matched value, else `-1`.
diff --git a/isArguments.js b/isArguments.js
index 318ccb227..c5650a56a 100644
--- a/isArguments.js
+++ b/isArguments.js
@@ -38,7 +38,7 @@ var propertyIsEnumerable = objectProto.propertyIsEnumerable;
  * // => false
  */
 function isArguments(value) {
-  // Safari 8.1 incorrectly makes `arguments.callee` enumerable in strict mode.
+  // Safari 8.1 makes `arguments.callee` enumerable in strict mode.
   return isArrayLikeObject(value) && hasOwnProperty.call(value, 'callee') &&
     (!propertyIsEnumerable.call(value, 'callee') || objectToString.call(value) == argsTag);
 }
diff --git a/isEmpty.js b/isEmpty.js
index 78f90a2d8..d9ff00245 100644
--- a/isEmpty.js
+++ b/isEmpty.js
@@ -3,10 +3,7 @@ import isArguments from './isArguments.js';
 import isArray from './isArray.js';
 import isArrayLike from './isArrayLike.js';
 import isBuffer from './isBuffer.js';
-import isFunction from './isFunction.js';
-import isObjectLike from './isObjectLike.js';
 import isPrototype from './_isPrototype.js';
-import isString from './isString.js';
 import nativeKeys from './_nativeKeys.js';
 
 /** `Object#toString` result references. */
@@ -60,24 +57,23 @@ var nonEnumShadows = !propertyIsEnumerable.call({ 'valueOf': 1 }, 'valueOf');
  */
 function isEmpty(value) {
   if (isArrayLike(value) &&
-      (isArray(value) || isString(value) || isFunction(value.splice) ||
-        isArguments(value) || isBuffer(value))) {
+      (isArray(value) || typeof value == 'string' ||
+        typeof value.splice == 'function' || isBuffer(value) || isArguments(value))) {
     return !value.length;
   }
-  if (isObjectLike(value)) {
-    var tag = getTag(value);
-    if (tag == mapTag || tag == setTag) {
-      return !value.size;
-    }
+  var tag = getTag(value);
+  if (tag == mapTag || tag == setTag) {
+    return !value.size;
+  }
+  if (nonEnumShadows || isPrototype(value)) {
+    return !nativeKeys(value).length;
   }
-  var isProto = isPrototype(value);
   for (var key in value) {
-    if (hasOwnProperty.call(value, key) &&
-        !(isProto && key == 'constructor')) {
+    if (hasOwnProperty.call(value, key)) {
       return false;
     }
   }
-  return !(nonEnumShadows && nativeKeys(value).length);
+  return true;
 }
 
 export default isEmpty;
diff --git a/isFunction.js b/isFunction.js
index 49eaa8cf2..a7ceb2b77 100644
--- a/isFunction.js
+++ b/isFunction.js
@@ -33,8 +33,7 @@ var objectToString = objectProto.toString;
  */
 function isFunction(value) {
   // The use of `Object#toString` avoids issues with the `typeof` operator
-  // in Safari 8 which returns 'object' for typed array and weak map constructors,
-  // and PhantomJS 1.9 which returns 'function' for `NodeList` instances.
+  // in Safari 8-9 which returns 'object' for typed array and other constructors.
   var tag = isObject(value) ? objectToString.call(value) : '';
   return tag == funcTag || tag == genTag;
 }
diff --git a/isPlainObject.js b/isPlainObject.js
index 6e561e213..0438043e0 100644
--- a/isPlainObject.js
+++ b/isPlainObject.js
@@ -6,10 +6,11 @@ import isObjectLike from './isObjectLike.js';
 var objectTag = '[object Object]';
 
 /** Used for built-in method references. */
-var objectProto = Object.prototype;
+var funcProto = Function.prototype,
+    objectProto = Object.prototype;
 
 /** Used to resolve the decompiled source of functions. */
-var funcToString = Function.prototype.toString;
+var funcToString = funcProto.toString;
 
 /** Used to check objects for own properties. */
 var hasOwnProperty = objectProto.hasOwnProperty;
diff --git a/lastIndexOf.js b/lastIndexOf.js
index 43a53a378..fb1dcdbd6 100644
--- a/lastIndexOf.js
+++ b/lastIndexOf.js
@@ -14,7 +14,7 @@ var nativeMax = Math.max,
  * @memberOf _
  * @since 0.1.0
  * @category Array
- * @param {Array} array The array to search.
+ * @param {Array} array The array to inspect.
  * @param {*} value The value to search for.
  * @param {number} [fromIndex=array.length-1] The index to search from.
  * @returns {number} Returns the index of the matched value, else `-1`.
diff --git a/lodash.default.js b/lodash.default.js
index f0a8c1c29..c3cdf3da7 100644
--- a/lodash.default.js
+++ b/lodash.default.js
@@ -45,7 +45,7 @@ import toInteger from './toInteger.js';
 import lodash from './wrapperLodash.js';
 
 /** Used as the semantic version number. */
-var VERSION = '4.14.2';
+var VERSION = '4.15.0';
 
 /** Used to compose bitmasks for function metadata. */
 var BIND_KEY_FLAG = 2;
diff --git a/package.json b/package.json
index 7645f7dad..640f021c4 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "lodash-es",
-  "version": "4.14.2",
+  "version": "4.15.0",
   "description": "Lodash exported as ES modules.",
   "keywords": "es6, modules, stdlib, util",
   "homepage": "https://lodash.com/custom-builds",
diff --git a/replace.js b/replace.js
index 68976c2fe..c14a16985 100644
--- a/replace.js
+++ b/replace.js
@@ -1,11 +1,5 @@
 import toString from './toString.js';
 
-/** Used for built-in method references. */
-var stringProto = String.prototype;
-
-/* Built-in method references for those with the same name as other `lodash` methods. */
-var nativeReplace = stringProto.replace;
-
 /**
  * Replaces matches for `pattern` in `string` with `replacement`.
  *
@@ -29,7 +23,7 @@ function replace() {
   var args = arguments,
       string = toString(args[0]);
 
-  return args.length < 3 ? string : nativeReplace.call(string, args[1], args[2]);
+  return args.length < 3 ? string : string.replace(args[1], args[2]);
 }
 
 export default replace;
diff --git a/size.js b/size.js
index 4ddd8c8c9..b808aaac4 100644
--- a/size.js
+++ b/size.js
@@ -1,7 +1,6 @@
 import baseKeys from './_baseKeys.js';
 import getTag from './_getTag.js';
 import isArrayLike from './isArrayLike.js';
-import isObjectLike from './isObjectLike.js';
 import isString from './isString.js';
 import stringSize from './_stringSize.js';
 
@@ -17,7 +16,7 @@ var mapTag = '[object Map]',
  * @memberOf _
  * @since 0.1.0
  * @category Collection
- * @param {Array|Object} collection The collection to inspect.
+ * @param {Array|Object|string} collection The collection to inspect.
  * @returns {number} Returns the collection size.
  * @example
  *
@@ -35,14 +34,11 @@ function size(collection) {
     return 0;
   }
   if (isArrayLike(collection)) {
-    var result = collection.length;
-    return (result && isString(collection)) ? stringSize(collection) : result;
+    return isString(collection) ? stringSize(collection) : collection.length;
   }
-  if (isObjectLike(collection)) {
-    var tag = getTag(collection);
-    if (tag == mapTag || tag == setTag) {
-      return collection.size;
-    }
+  var tag = getTag(collection);
+  if (tag == mapTag || tag == setTag) {
+    return collection.size;
   }
   return baseKeys(collection).length;
 }
diff --git a/sortedIndexOf.js b/sortedIndexOf.js
index d58d7b163..49ea3763f 100644
--- a/sortedIndexOf.js
+++ b/sortedIndexOf.js
@@ -9,7 +9,7 @@ import eq from './eq.js';
  * @memberOf _
  * @since 4.0.0
  * @category Array
- * @param {Array} array The array to search.
+ * @param {Array} array The array to inspect.
  * @param {*} value The value to search for.
  * @returns {number} Returns the index of the matched value, else `-1`.
  * @example
diff --git a/sortedLastIndexOf.js b/sortedLastIndexOf.js
index d59134708..f9738385e 100644
--- a/sortedLastIndexOf.js
+++ b/sortedLastIndexOf.js
@@ -9,7 +9,7 @@ import eq from './eq.js';
  * @memberOf _
  * @since 4.0.0
  * @category Array
- * @param {Array} array The array to search.
+ * @param {Array} array The array to inspect.
  * @param {*} value The value to search for.
  * @returns {number} Returns the index of the matched value, else `-1`.
  * @example
diff --git a/split.js b/split.js
index 4de901d1f..ad3681213 100644
--- a/split.js
+++ b/split.js
@@ -1,20 +1,14 @@
 import baseToString from './_baseToString.js';
 import castSlice from './_castSlice.js';
+import hasUnicode from './_hasUnicode.js';
 import isIterateeCall from './_isIterateeCall.js';
 import isRegExp from './isRegExp.js';
-import reHasComplexSymbol from './_reHasComplexSymbol.js';
 import stringToArray from './_stringToArray.js';
 import toString from './toString.js';
 
 /** Used as references for the maximum length and index of an array. */
 var MAX_ARRAY_LENGTH = 4294967295;
 
-/** Used for built-in method references. */
-var stringProto = String.prototype;
-
-/* Built-in method references for those with the same name as other `lodash` methods. */
-var nativeSplit = stringProto.split;
-
 /**
  * Splits `string` by `separator`.
  *
@@ -48,11 +42,11 @@ function split(string, separator, limit) {
         (separator != null && !isRegExp(separator))
       )) {
     separator = baseToString(separator);
-    if (separator == '' && reHasComplexSymbol.test(string)) {
+    if (!separator && hasUnicode(string)) {
       return castSlice(stringToArray(string), 0, limit);
     }
   }
-  return nativeSplit.call(string, separator, limit);
+  return string.split(separator, limit);
 }
 
 export default split;
diff --git a/startsWith.js b/startsWith.js
index cc67a4934..991da7a2d 100644
--- a/startsWith.js
+++ b/startsWith.js
@@ -10,7 +10,7 @@ import toString from './toString.js';
  * @memberOf _
  * @since 3.0.0
  * @category String
- * @param {string} [string=''] The string to search.
+ * @param {string} [string=''] The string to inspect.
  * @param {string} [target] The string to search for.
  * @param {number} [position=0] The position to search from.
  * @returns {boolean} Returns `true` if `string` starts with `target`,
diff --git a/toNumber.js b/toNumber.js
index 55609a814..430bf226c 100644
--- a/toNumber.js
+++ b/toNumber.js
@@ -1,4 +1,3 @@
-import isFunction from './isFunction.js';
 import isObject from './isObject.js';
 import isSymbol from './isSymbol.js';
 
@@ -51,7 +50,7 @@ function toNumber(value) {
     return NAN;
   }
   if (isObject(value)) {
-    var other = isFunction(value.valueOf) ? value.valueOf() : value;
+    var other = typeof value.valueOf == 'function' ? value.valueOf() : value;
     value = isObject(other) ? (other + '') : other;
   }
   if (typeof value != 'string') {
diff --git a/truncate.js b/truncate.js
index 0c3082c51..fe4156175 100644
--- a/truncate.js
+++ b/truncate.js
@@ -1,8 +1,8 @@
 import baseToString from './_baseToString.js';
 import castSlice from './_castSlice.js';
+import hasUnicode from './_hasUnicode.js';
 import isObject from './isObject.js';
 import isRegExp from './isRegExp.js';
-import reHasComplexSymbol from './_reHasComplexSymbol.js';
 import stringSize from './_stringSize.js';
 import stringToArray from './_stringToArray.js';
 import toInteger from './toInteger.js';
@@ -64,7 +64,7 @@ function truncate(string, options) {
   string = toString(string);
 
   var strLength = string.length;
-  if (reHasComplexSymbol.test(string)) {
+  if (hasUnicode(string)) {
     var strSymbols = stringToArray(string);
     strLength = strSymbols.length;
   }
diff --git a/words.js b/words.js
index 9edf1b217..c6d10c209 100644
--- a/words.js
+++ b/words.js
@@ -1,61 +1,7 @@
+import asciiWords from './_asciiWords.js';
+import hasUnicodeWord from './_hasUnicodeWord.js';
 import toString from './toString.js';
-
-/** Used to match non-compound words composed of alphanumeric characters. */
-var reBasicWord = /[a-zA-Z0-9]+/g;
-
-/** Used to compose unicode character classes. */
-var rsAstralRange = '\\ud800-\\udfff',
-    rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
-    rsComboSymbolsRange = '\\u20d0-\\u20f0',
-    rsDingbatRange = '\\u2700-\\u27bf',
-    rsLowerRange = 'a-z\\xdf-\\xf6\\xf8-\\xff',
-    rsMathOpRange = '\\xac\\xb1\\xd7\\xf7',
-    rsNonCharRange = '\\x00-\\x2f\\x3a-\\x40\\x5b-\\x60\\x7b-\\xbf',
-    rsPunctuationRange = '\\u2000-\\u206f',
-    rsSpaceRange = ' \\t\\x0b\\f\\xa0\\ufeff\\n\\r\\u2028\\u2029\\u1680\\u180e\\u2000\\u2001\\u2002\\u2003\\u2004\\u2005\\u2006\\u2007\\u2008\\u2009\\u200a\\u202f\\u205f\\u3000',
-    rsUpperRange = 'A-Z\\xc0-\\xd6\\xd8-\\xde',
-    rsVarRange = '\\ufe0e\\ufe0f',
-    rsBreakRange = rsMathOpRange + rsNonCharRange + rsPunctuationRange + rsSpaceRange;
-
-/** Used to compose unicode capture groups. */
-var rsApos = "['\u2019]",
-    rsBreak = '[' + rsBreakRange + ']',
-    rsCombo = '[' + rsComboMarksRange + rsComboSymbolsRange + ']',
-    rsDigits = '\\d+',
-    rsDingbat = '[' + rsDingbatRange + ']',
-    rsLower = '[' + rsLowerRange + ']',
-    rsMisc = '[^' + rsAstralRange + rsBreakRange + rsDigits + rsDingbatRange + rsLowerRange + rsUpperRange + ']',
-    rsFitz = '\\ud83c[\\udffb-\\udfff]',
-    rsModifier = '(?:' + rsCombo + '|' + rsFitz + ')',
-    rsNonAstral = '[^' + rsAstralRange + ']',
-    rsRegional = '(?:\\ud83c[\\udde6-\\uddff]){2}',
-    rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]',
-    rsUpper = '[' + rsUpperRange + ']',
-    rsZWJ = '\\u200d';
-
-/** Used to compose unicode regexes. */
-var rsLowerMisc = '(?:' + rsLower + '|' + rsMisc + ')',
-    rsUpperMisc = '(?:' + rsUpper + '|' + rsMisc + ')',
-    rsOptLowerContr = '(?:' + rsApos + '(?:d|ll|m|re|s|t|ve))?',
-    rsOptUpperContr = '(?:' + rsApos + '(?:D|LL|M|RE|S|T|VE))?',
-    reOptMod = rsModifier + '?',
-    rsOptVar = '[' + rsVarRange + ']?',
-    rsOptJoin = '(?:' + rsZWJ + '(?:' + [rsNonAstral, rsRegional, rsSurrPair].join('|') + ')' + rsOptVar + reOptMod + ')*',
-    rsSeq = rsOptVar + reOptMod + rsOptJoin,
-    rsEmoji = '(?:' + [rsDingbat, rsRegional, rsSurrPair].join('|') + ')' + rsSeq;
-
-/** Used to match complex or compound words. */
-var reComplexWord = RegExp([
-  rsUpper + '?' + rsLower + '+' + rsOptLowerContr + '(?=' + [rsBreak, rsUpper, '$'].join('|') + ')',
-  rsUpperMisc + '+' + rsOptUpperContr + '(?=' + [rsBreak, rsUpper + rsLowerMisc, '$'].join('|') + ')',
-  rsUpper + '?' + rsLowerMisc + '+' + rsOptLowerContr,
-  rsUpper + '+' + rsOptUpperContr,
-  rsDigits,
-  rsEmoji
-].join('|'), 'g');
-
-/** Used to detect strings that need a more robust regexp to match words. */
-var reHasComplexWord = /[a-z][A-Z]|[A-Z]{2,}[a-z]|[0-9][a-zA-Z]|[a-zA-Z][0-9]|[^a-zA-Z0-9 ]/;
+import unicodeWords from './_unicodeWords.js';
 
 /**
  * Splits `string` into an array of its words.
@@ -81,7 +27,7 @@ function words(string, pattern, guard) {
   pattern = guard ? undefined : pattern;
 
   if (pattern === undefined) {
-    pattern = reHasComplexWord.test(string) ? reComplexWord : reBasicWord;
+    return hasUnicodeWord(string) ? unicodeWords(string) : asciiWords(string);
   }
   return string.match(pattern) || [];
 }