[ES6] 03. The let keyword -- 1

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[ES6] 03. The let keyword -- 1

var message = "Hi"; { var message = "Bye"; } console.log(message); //Bye The message inside the block still has impact on the outside. Just remember that something like for, while if ... block, they don't create new scope. function blo…

[ES6] 05. The leg keyword -- 3. Block Scope

In ES6, IIFE is not necessary: // IIFE写法 (function () { var tmp = ...; ... }()); // 块级作用域写法 { let tmp = ...; ... } 另外,ES6也规定,函数本身的作用域,在其所在的块级作用域之内. function f() { console.log('I am outside!'); } (function () { if(false) { // 重复声明一次函数f function f() {…

[ES6] 04. The let keyword -- 2 Fiald case

Fiald case 1: let can work in it's block { let a = 10; var b = 1; } a // ReferenceError: a is not defined. b Case 2: Let has no "Hosting" Problem function do_something() { console.log(foo); // ReferenceError let foo = 2; } function do_something(…

ES6 Syntax and Feature Overview

View on GitHub Note: A commonly accepted practice is to use const except in cases of loops and reassignment. However, in this resource I'll be using let in place of var for all ES6 examples. Variable: x Object: obj Array: arr Function: func Parameter…

ES6中的数组

数组是js中很重要的数据类型,虽然在 ES5 中,关于数组的方法和属性很多.但为了更加简洁.高效的操作数组,ES6 中又在数组原型上和实例上新增了一些方法. 一.Array方法 1.1 Array.from() js中存在很多类似数组的对象,比如说获取的一组DOM元素,比如说函数的参数. 它们有着类似数组的属性,比如说键值对,或者 length 属性,但它们并不能使用数组里的方法. 要把一个类似数组的对象转换成一个真正的数组有时候可能很麻烦,就拿函数的参数来说,你需要通过如下方式: fu…

[Javascript] ES6 Class Constructors and the Super Keyword

When the ES6 class shipped back in 2015, a number of additional keywords came with it. Two of these are constructor and super. Both of these are specific to the class keyword and make working with classes manageable. Both are utilized when the new ke…