JavaScript修改this指向

修改this指向涉及到的方法：

bind、call、apply

bind说明：调用之后不会直接请求目标函数，而是会返回一个修改了this指向的函数，用于后面调用

function fun(old, gender) {
    console.log(this.name, old, gender)//"张三",12,"男"
}
let obj = {
    name: '张三'
}
let newfun = fun.bind(obj, 12)
newfun("男")

call说明：函数体调用call函数会直接请求目标函数，call里面用逗号方式传参

function fun1(old, gender) {
    console.log(this.name, old, gender)//"张三",30,"女"
}
let obj = {
    name: '张三'
}

let newfun = fun1.call(obj,30,'女')

apply说明：函数体调用apply函数会直接请求目标函数，call里面用数组方式传参

function fun1(old, gender) {
    console.log(this.name, old, gender)// "张三",30,"女"
}
let obj = {
    name: '张三'
}

let newfun = fun1.apply(obj, [30, '女'])