js中__proto__和prototype的区别和关系
1.对象有属性__proto__,指向该对象的构造函数的原型对象。
2.方法除了有属性__proto__,还有属性prototype，prototype指向该方法的原型对象。
深入浅出妙用 Javascript 中 apply、call、bind
***两道面试题***
关于js中伪数组
我们可以通过Array.prototype.slice.call(fakeArray)将伪数组转变为真正的Array对象。
JS的splice()方法和slice()方法
1.如何利用splice方法实现数组去重
2.es6去重数组
// 去除数组的重复成员 [...new Set(array)] 或者 Array.from(new Set(array));
ES6入门
js日期格式化
function formatDate(date) {var fmt="yyyy-MM"var o = {"M+": date.getMonth() + 1, //月份 "d+": date.getDate(), //日 "h+": date.getHours(), //小时 "m+": date.getMinutes(), //分 "s+": date.getSeconds(), //秒 "q+": Math.floor((date.getMonth() + 3) / 3), //季度 "S": date.getMilliseconds() //毫秒 };if (/(y+)/.test(fmt)) fmt = fmt.replace(RegExp.$1, (date.getFullYear() + "").substr(4 - RegExp.$1.length));for (var k in o)if (new RegExp("(" + k + ")").test(fmt)) fmt = fmt.replace(RegExp.$1, (RegExp.$1.length == 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));return fmt;}
getNowFormatDate(date) {var seperator1 = "-";var seperator2 = ":";var month = date.getMonth() + 1;var strDate = date.getDate();if (month >= 1 && month <= 9) {month = "0" + month;}if (strDate >= 0 && strDate <= 9) {strDate = "0" + strDate;}var currentdate = date.getFullYear() + seperator1 + month + seperator1 + strDate+ " " + date.getHours() + seperator2 + date.getMinutes()+ seperator2 + date.getSeconds();return currentdate;}
js Promise
简单测试一下， then函数可以返回新的promise。resolve()函数的返回值会传递到then(resolve, reject)函数中的resolve方法中。
Promise((resolve)=>{resolve(()=>{return 'xixi';})}).then((fun)=>{console.log(fun()); return Promise((resolve)=>{resolve(()=>{return 'haha'})}).then((fun)=>{console.log(fun())})}); 理解 Promise 简单实现的背后原理
//一个简单的Promise实现方案
function Promise(fn) {var value = null;var events = [];this.then = function(f) {events.push(f); return this;}function resolve(newValue) {var f = events.shift();f(newValue, resolve);}fn(resolve); } function a() { return new Promise(function(resolve) {console.log("get...");setTimeout(function() {console.log("get 1");resolve(1);}, 1000)}); } a().then(function(value, resolve) {console.log("get...");setTimeout(function() {console.log("get 2");resolve(2);}, 1000) }).then(function(value, resolve) {console.log(value) })这样就得到控制台如下的结果 get... get 1 get... get 2 2
JavaScript进阶之路——认识和使用Promise，重构你的Js代码 。一个较为复杂的Promise实现方案如下。
// see => http://promises-aplus.github.io/promises-spec/ // see => https://github.com/cujojs/when/blob/master/lib/makePromise.js ;(function(root, factory) {if (typeof module !== 'undefined' && module.exports) {// CommonJSmodule.exports = factory();} else if (typeof define === 'function' && define.amd) {// AMD / RequireJS define(factory);} else {root.Promise = factory.call(root);} }(this, function() {'use strict';function Promise(resolver) {if(!(this instanceof Promise)) return new Promise(resolver);this.status = 'pending';this.value;this.reason;// then may be called multiple times on the same promisethis._resolves = [];this._rejects = [];if(isFn(resolver)) resolver(this.resolve.bind(this), this.reject.bind(this));return this;};Promise.prototype.then = function(resolve, reject) {var next = this._next || (this._next = Promise());var status = this.status;var x;if('pending' === status) {isFn(resolve) && this._resolves.push(resolve);isFn(reject) && this._rejects.push(reject);return next;}if('resolved' === status) {if(!isFn(resolve)) {next.resolve(resolve);} else {try {x = resolve(this.value);resolveX(next, x);} catch(e) {this.reject(e);}}return next;}if('rejected' === status) {if(!isFn(reject)) {next.reject(reject);} else {try {x = reject(this.reason);resolveX(next, x);} catch(e) {this.reject(e);}}return next;}};Promise.prototype.resolve = function(value) {if('rejected' === this.status) throw Error('Illegal call.');this.status = 'resolved';this.value = value;this._resolves.length && fireQ(this);return this;};Promise.prototype.reject = function(reason) {if('resolved' === this.status) throw Error('Illegal call.');this.status = 'rejected';this.reason = reason;this._rejects.length && fireQ(this);return this;};// shortcut of promise.then(undefined, reject)Promise.prototype.catch = function(reject) {return this.then(void 0, reject);};// return a promise with another promise passing inPromise.cast = function(arg) {var p = Promise();if(arg instanceof Promise) return resolvePromise(p, arg);else return Promise.resolve(arg);};// return a promise which resolved with arg// the arg maybe a thanable object or thanable function or otherPromise.resolve = function(arg) {var p = Promise();if(isThenable(arg)) return resolveThen(p, arg);else return p.resolve(arg);};Promise.all = function(promises) {;};// return a promise which reject with reason// reason must be an instance of Error objectPromise.reject = function(reason) {if(!(reason instanceof Error)) throw Error('reason must be an instance of Error');var p = Promise();p.reject(reason);return p;};function resolveX(promise, x) {if(x === promise) promise.reject(new Error('TypeError'));if(x instanceof Promise) return resolvePromise(promise, x);else if(isThenable(x)) return resolveThen(promise, x);else return promise.resolve(x);};function resolvePromise(promise, promise2) {var status = promise2.status;if('pending' === status) {promise2.then(promise.resolve.bind(promise), promise.reject.bind(promise));}if('resolved' === status) promise.resolve(promise2.value);if('rejected' === status) promise.reject(promise2.reason);return promise;};function resolveThen(promise, thanable) {var called;var resolve = once(function(x) {if(called) return;resolveX(promise, x);called = true;});var reject = once(function(r) {if(called) return;promise.reject(r);called = true;});try {thanable.then.call(thanable, resolve, reject);} catch(e) {if(!called) throw e;else promise.reject(e);}return promise;};function fireQ(promise) {var status = promise.status;var queue = promise['resolved' === status ? '_resolves' : '_rejects'];var arg = promise['resolved' === status ? 'value' : 'reason'];var fn;var x;while(fn = queue.shift()) {x = fn.call(promise, arg);resolveX(promise._next, x);}return promise;};function noop () {};function isFn(fn) {return 'function' === type(fn);};function isObj(o) {return 'object' === type(o);};function type(obj) {var o = {};return o.toString.call(obj).replace(/\[object (\w+)\]/, '$1').toLowerCase();};function isThenable(obj) {return obj && obj.then && isFn(obj.then);};function once(fn) {var called;return function() {if(called) return;fn.apply(this, arguments);called = true;};};return Promise; }));
