JS函数重载

	function addMethod(object, name, fn){
    var old = object[name];//保存之前的fn
    object[name] = function(){
        if(fn.length === arguments.length){
            return fn.apply(this, arguments);
        }else if(typeof old === 'function'){
            return old.apply(this, arguments);//this=object
        }
    }
}
var people = {
  values: ["Dean Edwards", "Alex Russell", "Dean Tom"]
};
// 不传参数时，返回peopld.values里面的所有元素
addMethod(people, "find", function() {
  return this.values;
});

// 传一个参数时，按first-name的匹配进行返回
addMethod(people, "find", function(firstName) {
  var ret = [];
  for(var i = 0; i < this.values.length; i++) {
    if(this.values[i].indexOf(firstName) === 0) {
      ret.push(this.values[i]);
    }
  }
  return ret;
});

// 传两个参数时，返回first-name和last-name都匹配的元素
addMethod(people, "find", function(firstName, lastName) {
  var ret = [];
  for(var i = 0; i < this.values.length; i++) {
    if(this.values[i] === (firstName + " " + lastName)) {
      ret.push(this.values[i]);
    }
  }
  return ret;
});
// 测试：
console.log(people.find()); //["Dean Edwards", "Alex Russell", "Dean Tom"]
console.log(people.find("Dean")); //["Dean Edwards", "Dean Tom"]
console.log(people.find("Dean", "Edwards")); //["Dean Edwards"]