underscore.js _.extend[Object]

Copy all of the properties in the source objects over to the destination object, and return the destination object. It's in-order, so the last source will override properties of the same name in previous arguments.

将源对象属性复制到目标对象,并返回目标对象。它是有序的，所以最后的来源将覆盖以前参数名称相同的属性。

_.extend({name : 'moe'}, {age : 50});
=> {name : 'moe', age : 50}

源码:

  _.extend = function(obj) {
    each(slice.call(arguments, 1), function(source) {
      for (var prop in source) {
        obj[prop] = source[prop];
      }
    });
    return obj;
  };