call&Apply&Bind的手写

    call
    Function.prototype.callM = function(context = window, ...params) {
        let self = this //调用函数
        let fn = Symbol('fn') //设定唯一值方便删除
            //基本数据类型会包装，但后续再去掉方法会无效
            !(/^(object|function)$/i).test(typeof context) ? context = Object(context) : null
        context[fn] = self
        let res = context[fn](...params)
        delete context[fn]
        return res
    }

    apply
    Function.prototype.applyM = function(context, params) {
        context === null ? context = window : null
        let self = this //调用函数
        let fn = Symbol('fn') //设定唯一值方便删除
            //基本数据类型会包装，但后续再去掉方法会无效
            !(/^(object|function)$/i).test(typeof context) ? context = Object(context) : null
        context[fn] = self
        let res = context[fn](...params)
        delete context[fn]
        return res
    }

    bind
    Function.prototype.bindM = function(context, ...arg) {
        let self = this
        return function() {
            return self.apply(context, [...arg, ...arguments])
        }
    }