Add _#toString and _#valueOf.

Former-commit-id: adb194b6270fc72f794c69343891a2e891b90051

build.js

@@ -1413,6 +1413,9 @@
         // remove conditional `charCodeCallback` use from `_.max` and `_.min`
         source = source.replace(/!callback *&& *isString\(collection\)[\s\S]+?: */g, '');
 
+        // remove `lodash.prototype.toString` and `lodash.prototype.valueOf` assignments
+        source = source.replace(/ *lodash\.prototype\.(?:toString|valueOf) *=.+\n/g, '');
+
         // remove unused features from `createBound`
         if (buildMethods.indexOf('partial') == -1) {
           source = source.replace(matchFunction(source, 'createBound'), function(match) {

lodash.js

@@ -4043,6 +4043,22 @@
     return this;
   }
 
+  /**
+   * Produces the `toString` result of the wrapped value.
+   *
+   * @name toString
+   * @memberOf _
+   * @category Chaining
+   * @returns {String} Returns the string result.
+   * @example
+   *
+   * _([1, 2, 3]).toString();
+   * // => '1,2,3'
+   */
+  function wrapperToString() {
+    return String(this.__wrapped__);
+  }
+
   /**
    * Extracts the wrapped value.
    *
@@ -4196,7 +4212,9 @@
   // add `lodash.prototype.chain` after calling `mixin()` to avoid overwriting
   // it with the wrapped `lodash.chain`
   lodash.prototype.chain = wrapperChain;
+  lodash.prototype.toString = wrapperToString;
   lodash.prototype.value = wrapperValue;
+  lodash.prototype.valueOf = wrapperValue;
 
   // add all mutator Array functions to the wrapper.
   forEach(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(methodName) {

test/test-build.js

@@ -694,7 +694,11 @@
 
         equal(lodash.some([false, true, false]), true, '_.some: ' + basename);
         equal(lodash.template('${a}', object), '${a}', '_.template should ignore ES6 delimiters: ' + basename);
-        equal(lodash(1).clone() instanceof lodash, false, '_(...) wrapped values are not chainable by default: ' + basename);
+
+        object = lodash(1);
+        equal(object.clone() instanceof lodash, false, '_(...) wrapped values are not chainable by default: ' + basename);
+        equal(String(object) === '1', false, '_.prototype should not implement its own `toString` method: ' + basename);
+        equal(Number(object) === 1 , false, '_.prototype should not implement its own `valueOf` method: ' + basename);
 
         start();
       });

test/test.js

@@ -1922,6 +1922,28 @@
 
   /*--------------------------------------------------------------------------*/
 
+  QUnit.module('lodash(...).toString');
+
+  (function() {
+    test('should return the `toString` result of the wrapped value', function() {
+      var wrapped = _([1, 2, 3]);
+      equal(String(wrapped), '1,2,3');
+    });
+  }());
+
+  /*--------------------------------------------------------------------------*/
+
+  QUnit.module('lodash(...).valueOf');
+
+  (function() {
+    test('should return the `valueOf` result of the wrapped value', function() {
+      var wrapped = _(123);
+      equal(Number(wrapped), 123);
+    });
+  }());
+
+  /*--------------------------------------------------------------------------*/
+
   QUnit.module('lodash methods');
 
   (function() {