ES6 learning grammar ...

I. Scope (const var let)

Core: Minimize the use of var, using a constant const, let block-level scopes

5 button, click on the i button to achieve display i button is clicked.

  var btn = document.getElementsByTagName("button");

  // ES5 use closures to solve the problem var scope

  for (var i = 0; i < btn.length; i++) {

    (function(name){

      btn[i].addEventListener("click",function(){

      the console.log ( "This is the first" +  (name + . 1 )  + "button" )});       

    })(i);    

  }

  // ES6 using block-level scope to address the scope of the problem

  for (let i = 0; i < btn.length; i++) {    

      btn[i].addEventListener("click",function(){

      console.log("ES6这是第" + (i+1) + "个按钮")});     

    }

 

二、ES6语法- ``(tab键上键)

"" ''表示字符串，ES6中``也可表示字符串，且可以实现换行功能

如：

let n = 'a'

+'b';

输出ab

let m = `ab

`;

输出ab