es6 book

is "bound" to the area and is no longer affected by the external. var tmp = 123; if (true) { TMP = ' abc ';//referenceerror:tmp is not defined let tmp; } In the above code, the global variable TMP exists, but the block-level scope let also declares a local variable tmp, which causes the latter to bind the block-level scope, so the TMP assignment will be an error before let declares the variable. ES6 explicitly states that if a let and a cons

ECMAScript6 (ES6) is the latest JavaScript standard. Because the current version of ES6 was released in 2015, it is also called ECMAScript2015. Small programs support most of the new features of ES6. C... ECMAScript 6 (ES6) is the latest standard for JavaScript. Because the current version of

would when stitching a normal string. They don't work well with internationalized libraries (which can help you provide different languages for different users), and template strings don't format numbers and dates in a particular language, let alone use different languages at the same time. They cannot replace the status of the template engine, for example: mustache, nunjucks. The template string has no built-in looping syntax, so you cannot iterate through an array to construct a

Here's a brief look at the implications of these new language features for the development of React applications, which make React development simpler and more interesting.ClassSo far, the best embodiment of our use of es6+ to write React components is that we chose to use the class definition syntax. Instead of using the React.createclass method to define a component, we can define a bonafide ES6 class to

Previous wordsThe array is a basic JS object, and as time progresses, the rest of JS is evolving, and until the ES5 standard introduces some new methods to simplify the use of the array object. The ES6 standard continues to improve the array, adding many new features. This article describes in detail the ES6 array extensionCreate an arrayBefore ES6, there are two

Objective This article is mainly for ES6 to do a brief introduction, perhaps you do not know what ES6 is, in fact, it is a new JavaScript specification. In a time when everyone is busy, if you want to have a quick understanding of ES6, read on to learn about the six features of the latest generation of JavaScript, the most popular programming language today. In

注：ES6的一些新属性会显示语法错误，不过不会影响效果，在Languages里面也可以调；Let: used to define variables特点：只能在代码块里面使用,let拥有块级作用域;并且let不允许重复声明;比如: var a = 12; var a = 5; alert(a);//5; let a = 12; let a = 5; alert(a);//报错;Identifier ‘a‘ has already been declared代码块:{}包起来的代码,形成了一个作用域,比如if,for,while,json除外;块级作用域;var 只有函数作用域;用处: 自执行函数: for(let i = 0; i Const: Typically used to define constants常量:不允许修改;有些时候定的变量不希望被改变,这个不希望被改变的值就是常量;比如:let a = 5; a = 12; alert(a);//12;其实

How to use Set, WeakSet, es6setweakset in ES6 ES6 provides two new data structures: Set and WeakSet. Set is similar to an array, but the values of member variables are unique and there are no repeated values. WeakSet is also a set of non-repeated values, but can only be used to store objects. 1. Set usage (1) Set itself provides a constructor to generate a Set data structure. var s = new Set();[2,2,2,5,8,16

ES6 is extended for numeric types (number):1. A new notation for binary and octalES6 provides a new notation for binary and octal values, expressed in 0b (or 0B) and 0o (or 0o) respectively. For example:0b111110111 = = = 503 // true= = = 503 //trueSince ES5, in strict mode, octal is no longer allowed to use the prefix zero, so it is further clarified in the ES6 and is represented by 0o.If you want to con

Application code parsing of es6 in react and es6react code parsing Whether React or React-native, facebook officially recommends ES6 syntax. If ES6 is not used in projects, some problems may occur during the conversion, if there is no time for the system to learn ES6, it is enough to pay attention to some common writin

abandoned because it was too aggressive, Adobe's ActionScript 3.0 was the only implementation of ECMAScript Edition 4 (Flash almost unified the Web) By the year 2012, things have suddenly started to change. Everyone started pushing to stop support for older versions of Internet Explorer, and writing code in ECMAScript 5 (ES5) style became more feasible. At the same time, a new ECMAScript specification is starting to start. By this time, people began to become accustomed to the version of t

I am very excited about the new features discussed today, because this feature is the most magical feature of ES6. What does this "magic" mean? For beginners, this feature is completely different from the previous JS, and even some obscure. In a sense, it completely changes the normal behavior of the language, which is not "magic". Not only that, this feature simplifies the program code and changes the complex "callback stack" to the form of a strai

Please specify the Source: Grape City website, Grape City for developers to provide professional development tools, solutions and services, empowering developers. Original source: wanago.io/2018/07/16/webpack-4-course-part-one-entry-output-and-es6-modules/ How are you doing! Today we will start a Webpack 4 introductory tutorial. We will start with the basic concept of webpack, as the tutorial progresses. This time, we will learn the basics of m

This article describes the babel6.x installation process ~ First of all, you can use the Babel online conversion https://babeljs.io/repl/ Then go to the topic: Install Babel (command line environment, for babel6.x version) 1, first install BABEL-CLI (used in the terminal to use Babel) NPM install-g BABEL-CLI 2, then install the babel-preset-es2015 plugin NPM Install--save babel-preset-es2015 　　Note: The BABEL5 version defaults to include a variety of conversion plug-ins, however babel6.x

If you want to build a new JavaScript application with react, and you want to practice the new features in ES6 syntax, and you even want to create reusable components and post them to NPM, how exactly do you implement these requirements? How you publish ES6 code to NPM and how to use that code in subsequent projects. It took me some time to solve these problems and now I would like to share with you the new

This article mainly introduces the representation of JSES6 multi-line strings and connection strings, and compares and analyzes the representation and related operation skills of multi-line strings and connection strings in ES6 based on the specific instance form, if you need it, refer to the next article to introduce the representation of multiple lines of strings and connection strings in JS ES6, compare

]; Array.prototype.remDub= Array.prototype.remDub | |function(){ varJSON = {}; for(vari = 0; i This. length; i++) {json[ This[i]] | | (json[ This[i]] = This[i]); } vararr = []; for(varNameinchJSON) {Arr.push (json[name]); } returnarr;}; Console.log (Arr.remdub ()); //[1, ' A ', undefined, null, NaN]Above this use of JSON can be achieved, in fact, Es6 did not come out before using this is good, but

(connected to the previous article)Standard ES6 Features6. The new string method/new string methods7. Symbol/symbols8. String Template/template StringsThe new string method/new string methodsCodepointat () and string.fromcodepoint ()JS interior is in the form of UTF-16 (each character length is fixed to 16 bits, 2 bytes) to store character encoding. In terms of Chinese characters, most of the Chinese characters are stored in 2-byte form, but some Chin

As the future of JavaScript, ES6 has arrived. As a finished standard, ES6 brings many new features that make it still competitive in today's web world. All aspects of ES6 are not necessarily suitable for you, this Assembly briefly introduces some of the new features that are handy and feasible.I write JavaScript code that prefers to use single quotes to define st

1 Syntax support settings Preferences > Languages Frameworks > JavaScript Just configure the ECMAScript version hereAfter configuration2 Automatic transcoding to ES5 File Watcher + Babel (ES6 transcoding) You may want to have better compatibility with your code, but the current ES6 is definitely not supported by all browsers, so we'll use the