JS模拟实现题目（new debounce throwee 等）

模拟new实现

function newObject() {
let obj = new Object();
let Con = [].shift.apply(arguments)
obj.proto = Con.prototype;
let res = Con.apply(obj,arguments)
return typeof res == "object" ? res : obj;
}

模拟instanceOf

function instanceOf(left,right) {
let proto = left.proto;
let prototype = right.prototype
while(true) {
if(proto == null) return false
if(proto == prototype) return true
proto = proto.proto;
}
}

防抖 debounce

function debounce(fn,wait=50,immediate) {
let timer;
return function() {
if(immediate) {
fn.apply(this,arguments)
}
if(timer) clearTimeout(timer)
timer = setTimeout(()=> {
fn.apply(this,arguments)
},wait)
}
}

节流 throttle

function throttle(fn,wait=50) {
let timer;
return function() {
if(!timer) {
timer = setTimeout(()=> {
fn.apply(this,arguments)
timer = null
},wait)
}
}
}

jsonp

function jsonp(url,callback,success) {
let script = document.createElement("script")
script.src = url;
script.async = true;
script.type = "text/javascript"
window[callback] = function(data) {
success && success(data)
}
document.body.append(script)
}

继承

function a() {
this.a = "a"
}
a.prototype.test = function() {
console.log(this.a)
}

function b() {
a.call(this);
this.b = "b"
}

function tmp() {}
tmp.prototype = a.prototype;
b.prototype = new tmp();
b.prototype.construcotr = b;

模拟call

Function.prototype.mycall = function(content = window) {
content.fn = this;
let args = [...arguments].slice(1);
let result = content.fn(...args);
delect content.fn;
return result;
}

模拟apply

Function.prototype.myapply = function(content = window) {
content.fn = this;
let result;

if(argument[1]) {
result = content.fn(...argument[1]);
} else {
result = content.fn();
}
delect content.fn;
return result;
}

模拟bind

Function.prototype.mybind = function(content) {
if(typeof this != "function") {
throw Error("not a function")
}
let fn = this;
let args = [...arguments].slice(1);

let resFn = function() {
return fn.apply(this.instance == resFn ? this : content,args.concat(...arguments) )
}
function tmp() {}
tmp.prototype = this.prototype;
resFn.prototype = new tmp();

return resFn;
}