Use native Object.create when available, optimize the creation of lodash instances, and ensure methods like forEach return the existing wrapper object when chaining, instead of creating a new one.

Former-commit-id: fa9ec371ba23ce8c35c15a66dd9b1f09f183b3a9
2026-02-02 16:17:50 +00:00 · 2013-03-03 01:19:04 -08:00
parent aa49ce5c56
commit 8825a094ae
3 changed files with 104 additions and 39 deletions
--- a/build.js
+++ b/build.js
@@ -381,21 +381,26 @@
      ].join('\n' + indent);
    });

-    // add `__chain__` checks to `_.mixin`
-    source = source.replace(matchFunction(source, 'mixin'), function(match) {
-      return match.replace(/^( *)return new lodash.+/m, function() {
-        var indent = arguments[1];
-        return indent + [
-          '',
-          'var result = func.apply(lodash, args);',
-          'if (this.__chain__) {',
-          '  result = new lodash(result);',
-          '  result.__chain__ = true;',
-          '}',
-          'return result;'
-        ].join('\n' + indent);
-      });
-    });
+    // replace `_.mixin`
+    source = replaceFunction(source, 'mixin', [
+      'function mixin(object) {',
+      '  forEach(functions(object), function(methodName) {',
+      '    var func = lodash[methodName] = object[methodName];',
+      '',
+      '    lodash.prototype[methodName] = function() {',
+      '      var args = [this.__wrapped__];',
+      '      push.apply(args, arguments);',
+      '',
+      '      var result = func.apply(lodash, args);',
+      '      if (this.__chain__) {',
+      '        result = createWrapper(result);',
+      '        result.__chain__ = true;',
+      '      }',
+      '      return result;',
+      '    };',
+      '  });',
+      '}'
+    ].join('\n'));

    // replace wrapper `Array` method assignments
    source = source.replace(/^(?: *\/\/.*\n)*( *)each\(\['[\s\S]+?\n\1}$/m, function(match, indent) {
@@ -1174,7 +1179,7 @@

    // remove `noCharByIndex` from `_.toArray`
    source = source.replace(matchFunction(source, 'toArray'), function(match) {
-      return match.replace(/noCharByIndex[^:]+:/, '');
+      return match.replace(/(return\b).+?noCharByIndex[^:]+:\s*/, '$1 ');
    });

    // `noCharByIndex` from `iteratorTemplate`
@@ -1753,7 +1758,7 @@
      if (isModern) {
        // remove `_.isPlainObject` fallback
        source = source.replace(matchFunction(source, 'isPlainObject'), function(match) {
-          return match.replace(/!getPrototypeOf.+?: */, '');
+          return match.replace(/!getPrototypeOf[^:]+:\s*/, '');
        });

        if (!isMobile) {
@@ -1927,7 +1932,7 @@
          '  }',
          '  var isArr = className == arrayClass;',
          '  if (!isArr) {',
-          '    if (a.__wrapped__ || b.__wrapped__) {',
+          '    if (a instanceof lodash || b instanceof lodash) {',
          '      return isEqual(a.__wrapped__ || a, b.__wrapped__ || b, stackA, stackB);',
          '    }',
          '    if (className != objectClass) {',
@@ -1989,6 +1994,19 @@
          '}'
        ].join('\n'));

+        // replace `lodash`
+        source = replaceFunction(source, 'lodash', [
+          'function lodash(value) {',
+          '  if (value instanceof lodash) {',
+          '    return value;',
+          '  }',
+          '  if (!(this instanceof lodash)) {',
+          '    return new lodash(value);',
+          '  }',
+          '  this.__wrapped__ = value;',
+          '}'
+        ].join('\n'));
+
        // replace `_.omit`
        source = replaceFunction(source, 'omit', [
          'function omit(object) {',
@@ -2189,7 +2207,7 @@
        // remove conditional `charCodeCallback` use from `_.max` and `_.min`
        _.each(['max', 'min'], function(methodName) {
          source = source.replace(matchFunction(source, methodName), function(match) {
-            return match.replace(/!callback *&& *isString\(collection\)[\s\S]+?: */g, '');
+            return match.replace(/(return\b).+?callback *&& *isString[^:]+:\s*/g, '$1 ');
          });
        });

@@ -2469,9 +2487,14 @@
            '  lodash[methodName] = func;',
            '',
            '  lodash.prototype[methodName] = function() {',
-            '    var args = [this.__wrapped__];',
+            '    var value = this.__wrapped__,',
+            '        args = [value];',
+            '',
            '    push.apply(args, arguments);',
-            '    return new lodash(func.apply(lodash, args));',
+            '    var result = func.apply(lodash, args);',
+            "    return (value && typeof value == 'object' && value == result)",
+            '      ? this',
+            '      : createWrapper(result);',
            '  };',
            '});'
          ].join('\n' + indent);
--- a/lodash.js
+++ b/lodash.js
@@ -174,6 +174,7 @@

    /* Native method shortcuts for methods with the same name as other `lodash` methods */
    var nativeBind = reNative.test(nativeBind = slice.bind) && nativeBind,
+        nativeCreate = reNative.test(nativeCreate = Object.create) && nativeCreate,
        nativeIsArray = reNative.test(nativeIsArray = Array.isArray) && nativeIsArray,
        nativeIsFinite = context.isFinite,
        nativeIsNaN = context.isNaN,
@@ -319,7 +320,7 @@
     */
    function lodash(value) {
      // exit early if already wrapped, even if wrapped by a different `lodash` constructor
-      if (value && typeof value == 'object' && value.__wrapped__) {
+      if (value && typeof value == 'object' && hasOwnProperty.call(value, '__wrapped__')) {
        return value;
      }
      // allow invoking `lodash` without the `new` operator
@@ -644,9 +645,7 @@
        }
        if (this instanceof bound) {
          // ensure `new bound` is an instance of `func`
-          noop.prototype = func.prototype;
-          thisBinding = new noop;
-          noop.prototype = null;
+          thisBinding = createObject(func.prototype);

          // mimic the constructor's `return` behavior
          // http://es5.github.com/#x13.2.2
@@ -769,6 +768,33 @@
      );
    }

+    /**
+     * Creates a new object that inherits from the given `prototype` object.
+     *
+     * @private
+     * @param {Object} prototype The prototype object.
+     * @returns {Object} Returns the new object.
+     */
+    var createObject = nativeCreate || function(prototype) {
+      noop.prototype = prototype;
+      var result = new noop;
+      noop.prototype = null;
+      return result;
+    };
+
+    /**
+     * A fast path for creating `lodash` wrapper objects.
+     *
+     * @private
+     * @param {Mixed} value The value to wrap in a `lodash` instance.
+     * @returns {Object} Returns a `lodash` instance.
+     */
+    function createWrapper(value) {
+      var result = createObject(lodash.prototype);
+      result.__wrapped__ = value;
+      return result;
+    }
+
    /**
     * A function compiled to iterate `arguments` objects, arrays, objects, and
     * strings consistenly across environments, executing the `callback` for each
@@ -1562,7 +1588,7 @@

        case numberClass:
          // treat `NaN` vs. `NaN` as equal
-          return a != +a
+          return (a != +a)
            ? b != +b
            // but treat `+0` vs. `-0` as not equal
            : (a == 0 ? (1 / a == 1 / b) : a == +b);
@@ -1576,7 +1602,7 @@
      var isArr = className == arrayClass;
      if (!isArr) {
        // unwrap any `lodash` wrapped values
-        if (a.__wrapped__ || b.__wrapped__) {
+        if (hasOwnProperty.call(a, '__wrapped__ ') || hasOwnProperty.call(b, '__wrapped__')) {
          return isEqual(a.__wrapped__ || a, b.__wrapped__ || b, callback, thisArg, stackA, stackB);
        }
        // exit for functions and DOM nodes
@@ -2748,7 +2774,7 @@
          }
        }
      } else {
-        callback = !callback && isString(collection)
+        callback = (!callback && isString(collection))
          ? charAtCallback
          : createCallback(callback, thisArg);

@@ -2817,7 +2843,7 @@
          }
        }
      } else {
-        callback = !callback && isString(collection)
+        callback = (!callback && isString(collection))
          ? charAtCallback
          : createCallback(callback, thisArg);

@@ -3181,7 +3207,7 @@
     */
    function toArray(collection) {
      if (collection && typeof collection.length == 'number') {
-        return noCharByIndex && isString(collection)
+        return (noCharByIndex && isString(collection))
          ? collection.split('')
          : slice(collection);
      }
@@ -3848,7 +3874,7 @@

      while (low < high) {
        var mid = (low + high) >>> 1;
-        callback(array[mid]) < value
+        (callback(array[mid]) < value)
          ? low = mid + 1
          : high = mid;
      }
@@ -4573,9 +4599,14 @@
        var func = lodash[methodName] = object[methodName];

        lodash.prototype[methodName] = function() {
-          var args = [this.__wrapped__];
+          var value = this.__wrapped__,
+              args = [value];
+
          push.apply(args, arguments);
-          return new lodash(func.apply(lodash, args));
+          var result = func.apply(lodash, args);
+          return (value && typeof value == 'object' && value == result)
+            ? this
+            : createWrapper(result);
        };
      });
    }
@@ -5130,7 +5161,7 @@
          var result = func(this.__wrapped__, callback, thisArg);
          return callback == null || (thisArg && typeof callback != 'function')
            ? result
-            : new lodash(result);
+            : createWrapper(result);
        };
      }
    });
@@ -5172,7 +5203,7 @@
    each(['concat', 'slice', 'splice'], function(methodName) {
      var func = arrayRef[methodName];
      lodash.prototype[methodName] = function() {
-        return new lodash(func.apply(this.__wrapped__, arguments));
+        return createWrapper(func.apply(this.__wrapped__, arguments));
      };
    });

@@ -5190,7 +5221,7 @@
          if (value.length === 0) {
            delete value[0];
          }
-          return isSplice ? new lodash(result) : result;
+          return isSplice ? createWrapper(result) : result;
        };
      });
    }
--- a/test/test.js
+++ b/test/test.js
@@ -179,8 +179,8 @@
      ok(_() instanceof _);
    });

-    test('should return passed LoDash instances', function() {
-      var wrapped = _([]);
+    test('should return passed `lodash` instances', function() {
+      var wrapped = _(false);
      equal(_(wrapped), wrapped);
    });
  }());
@@ -810,11 +810,16 @@
  QUnit.module('lodash.forEach');

  (function() {
-    test('returns the collection', function() {
+    test('should return the collection', function() {
      var collection = [1, 2, 3];
      equal(_.forEach(collection, Boolean), collection);
    });

+    test('should return the existing wrapper when chaining', function() {
+      var wrapper = _([1, 2, 3]);
+      equal(wrapper.forEach(Boolean), wrapper);
+    });
+
    _.each({
      'literal': 'abc',
      'object': Object('abc')
@@ -901,6 +906,12 @@
  _.each(['assign', 'defaults', 'merge'], function(methodName) {
    var func = _[methodName];

+    test('should return the existing wrapper when chaining', function() {
+      var wrapper = _({ 'a': 1 });
+      equal(wrapper[methodName]({ 'b': 2 }), wrapper);
+    });
+
+
    test('lodash.' + methodName + ' should assign problem JScript properties (test in IE < 9)', function() {
      var object = {
        'constructor': '0',