JavaScript中关于自定义实现call、apply、bind详解

原理： https://blog.csdn.net/qq_40479190/article/details/78324270

示例： apply

Function.prototype.myApply = function(context) {
　　let context = context || window
　　context.fn = this
　　let result
　　if (arguments[1]){
　　　　result = context.fn(...arguments[1])
　　} else {
　　　　result = context.fn()
　　}
　　delete context.fn
　　return result
}

示例：call 

Function.prototype.myCall function (context){
    let context = context || window
    context.fn = this
    let args = [...arguments].slice(1)
    let result = context.fn(...args)
    delete context.fn
    return result
}