知识总结

call()-apply()-bind()

能干什么：

• 动态改变某个函数运行时的上下文（context）

• 可以改变函数体内部的this指向

举个例子：

cat.call(dog,a,b) = cat.apply(dog,[a,b]) = (cat.func.bind(dog,a,b))() = dog.cat.func(a,b)

function Cat(name) {
    this.name = name;
    this.catchMouse = catchMouse;

    function catchMouse(name1, name2) {
        console.log(this.name + ' caught 2 mouse! They call ' + name1 + ' and ' + name2 + '.');
    }
}

function Dog(o) {
    this.name = o;
    this.biteCriminals = biteCriminals;

    function biteCriminals(name1, name2) {
        console.log(this.name + ' bite 2 criminals! Their name is ' + name1 + ' and ' + name2 + '.');
    }
};

var kitty = new Cat('Kitty');
var doggy = new Dog('Doggy');

kitty.catchMouse('Mickey', 'Minnie');
doggy.biteCriminals('Tom', 'Jerry');

kitty.catchMouse.call(doggy, 'Mickey', 'Minnie');
kitty.catchMouse.apply(doggy, ['Mickey', 'Minnie']);
(kitty.catchMouse.bind(doggy, 'Mickey', 'Minnie'))();