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;
}