Function.prototype.callPolyfill= function(){
// 获取参数列表
let args = [...arguments]
// 获取要绑定的that
let that = args[0] || window
// 将原函数复制绑定当前的that
that.fn = this
// 执行复制绑定that后的函数
const result = that.fn(...args.slice(1))
// 解绑，防止破环that
delete that.fn
// 返回结果
return result
}
Function.prototype.applyPolyfill = function(){
// 获取参数列表
let args = [...arguments]
// 获取要绑定的that
let that = args[0] || window
// 将原函数复制绑定当前的that
that.fn = this
// 执行复制绑定that后的函数
args[1] = args[1] || []
const result = that.fn(...args[1])
// 解绑，防止破环that
delete that.fn
// 返回结果
return result
}
Function.prototype.bindPolyfill= function(){
// 获取参数列表
let args = [...arguments]
// 获取要绑定的that
let that = args[0] || window
let targetThis = this
return function(){
// 将原函数复制绑定到当前的that
that.fn = targetThis
const result = that.fn(...args.slice(1),...arguments)
// 解绑，防止破环that
delete that.fn
// 返回结果
return result
}
}
