javascript call/apply/this使用实例讲解

function add(a,b){
    console.log(this);
    return a+b;
}
add(1,2)   // 默认window调用，this指向window

var math = {
    add:function(a,b){
        console.log(this);
        return a+b;
    }
}
math.add(1,2)  // this指向math

var name = "WINDOW";
var someone = {
    name: "yource"
};

/** 一般写法 **/
function greet1(person) {
    var reply = "Hello, " + person.name;
    console.log(reply)
}

greet1(someone);  // Hello, yource

/** 使用call/apply **/
function greet2() {
    var reply = "Hello, " + this.name;
    console.log(reply)
}

greet2();  // Hello, WINDOW
greet2.call(someone);   // Hello, yource
greet2.apply(someone);  // Hello, yource

/*apply()方法*/
function.apply(thisObj[, argArray])

/*call()方法*/
function.call(thisObj[, arg1[, arg2[, [,...argN]]]]);