es6 book

This article describes in detail how to use Set and WeakSet in ES6. If you are interested, refer to the two new data structures-Set and WeakSet in ES6. 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

ES6 and canvas implement the following effect on the mouse ball and es6canvas ball Recently, I was bored. I read ES6 syntax and used canvas to implement animation effects. As the mouse moves, there will be an animation where the ball follows and disappears automatically. First, the html part is currently a canvas tag. 1 Secondly, the css section does not consider appearance. If you like it, you can add you

: [ /// New Webpack.optimize.UglifyJsPlugin ({ // compress: { // warnings:false // } // }) // ]};　　Module features include jsx to Js,es6 es5,scss to CSS,Here I use a built-in plugin for Webpack, which UglifyJsPlugin allows you to compress the generated files, which I commented out.1.3 On the CodeThen we'll give you the important code.Index.htmlDOCTYPE HTML>HTMLLang= "en">Head> MetaCharSet= "UTF-

There are two new commands in ES6: Let and Const.Let command: let is used to declare a variable, similar to Var, but the declared variable is valid only in the code block, there is no promotion of the variable, there is a temporary dead zone.1. Valid only in code blocksUnlike the Var command, a let declared variable is only valid in a block of code, such as{ = 1; var b = 2;}Console.log (b); Print 2;console.log (a); This would cause error.2. There is

I believe many people have used export, export default, import, but what is the difference between them?In JavaScript ES6, export and export default can be used for exporting constants, functions, files, modules, etc., which you can import in other files or modules in such a way that they can be import+(常量 | 函数 | 文件 | 模块)名 used, but in a file or module, Export, import can have multiple, export default only one.Specific use:1.//demo1.jsexport const str

Today began the study of ES5 and ES6.1. What is ES5 and ES6?is the fifth and sixth version of ECMAScript, so the question is, what is ECMAScript? First it is a scripting language, called JavaScript, that is standardized by the ECMA international through ECMA-262, but in fact JavaScript is the implementation and extension of the ECMA-262 standard ( Said so much in fact it is a set of JavaScript standards, the specific name of the origin and history can

Destructuring: Array:let [firstvalue] = [1]; Firstvalue:1Let C, D;Let [A, b] = [C, d] = [1, 2];var [head, ... tail] = [1, 2, 3, 4]; Tail: [2,3,4]You can swap variables:let [x, y] = [' ax ', ' why '];[x, Y] = [y, x]; X:why, Y:axConst ALL = [' ax ', ' Why ', ' Zet '];const [,, z] = all; Z:setNested arrays can also:const USER = [[' Some ', ' one '], 23];const [[FirstName, surname], age] = user;for (var [a, b] of [[1, 2]]) {}//a:1, B:2Strings can also be oh:Let [A, B, c] = ' abc '; [A, B, c]: [' A '

(); app.use ( //this is the most important part of this example, we do a series of asynchronous operations , but there is no callback var city = yield geolocation.getcityasync ( this.req.ip); var forecast = yield weather.getforecastasync (city); this.body = ' Today, ' + City + ' would be ' + Forecas T.temperature + ' degrees. '; }); app.listen (8080); Does it look familiar? Koa just like we just did, encapsulates the details of the processing and invocation methods o

Look at the ES6 to feel a variety of data structure of the traversal method a lot of good confusion, write down the summary, see what the difference in the application scenarioArray:ES5:(1) Array.prototype.forEach (function (Item,index,array) {...})(2) Array.prototype.map (function (Value,index,array) {...//return value, which is inserted into a new array}) is mapped to a new array(3) Array.prototype.some (the function (item) {...//condition}) an item

What is ES6ECMAScript 6 abbreviation ES6, officially released in June 2015 ~ ECMAScript is the international standard of JavaScript language.We are guided by the principle of 28, a good grasp of common, useful ~ can let us get started faster ~ ~ ~1 declaring Variable const let VARES6 the previous var keyword to declare a variable, no matter where it is declared, there is a variable promotion. The variable is created in advance ~Scopes are only global

1. ES6 added a let command to declare a variable. It is used in a similar way var , but the declared variable is let valid only within the code block where the command resides. { var a = 1; = 1; } A; b;/Let does not have variable promotion like Var , that is, variables must be declared before they can be used2, block-level scopeES5 only global scope and function scope, no block-level scopeDifference between

, so the output is 1. However, the parameters of the function can be accessed using the remaining parameters in the arrow function.In JavaScript, the This binding is a more complex mechanism because the value of this point is not determined until it is actually executed, and it is not necessarily the value that is pointed to when it is defined. There is no this binding in the arrow function, which means that the value of this is determined when the function is defined and does not change the val

1.let command1) Basic usageThe Let command is a new command for declaring a variable, similar to Var, but the ES6 variable is valid only within the code block where the Let command resides.2) "Declaration in advance" does not existLet declaration of the variable does not exist "declaration in advance", the variable must be used after the declaration, otherwise it will cause an error, for example:Console.log (a); // undefinedconsole.log (b); // Error!

What is ECMAScript? First, we all know that JavaScript consists of three parts: Ecmascript,dom,bom;one of the ECMAScript is the syntax specification for JavaScript. ECMAScript defines a lot of things, such as: Syntax-----parsing rules, keywords, statements, declarations, actions, etc. Type-----Boolean, number, String, object, etc. Prototypes and inheritance Built-in objects, standard libraries of functions----------JSON, Math, array methods, object methods, etc. Browser

DOCTYPE HTML>HTMLLang= "zh"> Head> MetaCharSet= "UTF-8" /> Metaname= "Viewport"content= "Width=device-width, initial-scale=1.0" /> Metahttp-equiv= "X-ua-compatible"content= "Ie=edge" /> title>ES6 classtitle> Head> Body> Scripttype= "Text/javascript">class Person {//instance MethodConstructor (name) { This. Name=name; } //prototype Chain MethodSayname () {Console.log ( This. Name)} }

Rest Parameters:In ES5, when you don ' t know how many paramters would be passed in, you can use arguments:function () { = 0; for (Let i = 0; i ) { + = arguments[i] ; } return = SUM (n/a);In ES6, you can use Rest params:function (... numbers) {= 0; for (Let i = 0; i ) { + = numbers[i] ; } return result;};function () { It (function() { function(name, ... numbers) {= 0;

The following describes how to use webpack with babel to convert es6 to an ultra-simple instance of es5 and webpackes5. Today, I got started with webpack. The first time I used webpack for transcoding, it turned out to be a bit confusing. Haha. The process is attached below Create folders and initialize them. First, install webpack globally. npm install webpack --save-dev Then install babel npm install --save-dev babel-core babel-preset-es2015 npm in

In Javascript ES6, the use of the data type Symbol is described in detail. Introduction Symbol is a special and unchangeable data type. It can be used as an identifier of an object property to indicate unique values. The Symbol object is an implicit object wrapper of the symbol primitive data type. It is the seventh data type in the JavaScript language. The first six data types are Undefined, Null, Boolean, String, Number, and Object. Syntax Symbol([d

ES6 new features array, Math and extended operator usage example, es6math This article describes the new features of ES6, including array, Math, and extended operator usage. We will share this with you for your reference. The details are as follows: I. Array Some new static methods are added to the Array object, and some new methods are also added to the Array prototype. 1. Array. from create an Array insta

ES6 new feature 6: Detailed description of the promise object instance, es6promise This example describes the promise object of the new ES6 feature. We will share this with you for your reference. The details are as follows: 1. Introduction to promise It is an object, which is similar to other JavaScript objects. Second, it acts as a proxy ),Acts as an intermediary between asynchronous operations and callba