underscore的bind和bindAll方法

bind方法和bindAll方法都是用来设定函数的this值的，区别是调用方式不同。

var xiaoming = {
    say:function(){
        console.log('I am xiaoming');
    }
}

//bind
var func = bind(xiaoming, xiaoming.say);
func(); // I am xiaoming

//bindAll
bindAll(xiaoming, 'say');
var func = xiaoming.say;
func(); // I am xiaoming

bind和bindAll都是改变函数的this指向，然后返回一个新的函数，永久的指向这个this指向

举例

function Person(name,age){
    this.name = name;
    this.age = age;

    bindAll(this, 'sayName', 'sayAge');
}

Person.prototype.sayName = function(){
    console.log(this.name);
}

Person.prototype.sayAge = function(){
    console.log(this.age);
}

var person = new Person('xiaoming',26);
var func = person.sayName;
func();

$('button').click(person.sayAge);

无论如何调用，sayName和sayPerson的this都指向person对象。