代码语言:javascript 代码运行次数:0 运行 AI代码解释 //weakmap.jsfunctionusageSize(){constused=process.memoryUsage().heapUsed;returnMath.round(used/1024/1024*100)/100+'M';}global.gc();console.log(usageSize());// ≈ 3.23Mletarr=newArray(5*1024*1024);constmap=newWeakMap();map.set(arr,1...
而为了实现 async/await 在 await 结束之后要重新原函数的上下文并提供 await 之后的结果,规范定义此时还需要一个 Promise,这个在 V8 团队看来是没有必要的,所以他们建议规范去除这个特性。 最后的最后,官方还建议我们:多使用 async/await 而不是手写 Promise 代码,多使用 JavaScript 引擎提供的 Promise 而不是自己...
精读《What's new in javascript》 1. 引言 本周精读的内容是:Google I/O 19。 2019 年 Google I/O 介绍了一些激动人心的 JS 新特性,这些特性有些已经被主流浏览器实现,并支持 polyfill,有些还在草案阶段。 我们可以看到 JS 语言正变得越来越严谨,不同规范间也逐渐完成了闭环,而且在不断吸纳其他语言的优秀...
JavaScript 1.8 is part of Gecko 1.9 (which is incorporated into Firefox 3). Array extras There are two new iterative Array methods included in JavaScript 1.8, specifically: •reduce()- runs a function on every item in the array and collects the results from previous calls. if (!Array.prot...
static SET_BAR_HEIGHT="set_bar_height"; constructor(parent) { this.container = parent; this.menuUl=this.container.firstElementChild; this.elem = this.createElem(); //侦听菜单的点击事件,动态改变滚动条的高度 document.addEventListener(ScrollBar.SET_BAR_HEIGHT,()=>this.setBarHeight()); ...
1...this 指向的类型 刚开始学习 JavaScript 的时候,this总是最能让人迷惑,下面我们一起看一下在 JavaScript 中应该如何确定 this的指向。...这种场景我们遇到的比较多的是 setTimeout 和 setInterval,如果回调函数不是箭头函数,那么其中的 this指向的就是全局对象。...Function.prototype.bind() - JavaScript...
共享内存。setTimeout等异步,是取现在当时的a的值。执行第一个setTimeout的时候,a=3,已经执行了。 二、全局变量和new变成全局的 varfoo=10;vara=1;varmain =function(){//a=10;console.log(a); a=20; console.log(this.foo);this.foo=foo; ...
Expand your reach with tools to broaden Javascript development Access our API documentation, resource center, and educational courses to adapt your skills and grow as a partner. With Shopify’s Partner Program, we make sure our partners are set up for success, whether they’re building apps or...
To allow JavaScript/TypeScript projects to also be easily debugged using Visual Studio Code, we’ve included a launch.json file to the project template. This file will be used to set your launch configurations in Visual Studio, as well as in VS Code. As a result, you will be able to ...
3setTimeout(function(){ 4someFunction(); 5},100); 6} Perhaps, code looks logic and normal, and in some situations it may work, but it’s still not working code. The problem is that as soon assomeFunctionwill try to access“this”variable inside of it, code will break. The reason...