ES6 学习

1. 块级作用域
   以前定义变量用var：

var name = "张三";

现在使用let

let name = "张三" 

块的概念：

if(true) {
  let name = "张三";
}```
console.log(name);
会报错误:name未定义，也就是说let定义的变量只能在块级作用域中使用。

2. const 定义常量
const name = "张三";
name = "李四";
浏览器报错，不可以修改。

const list = [];
list.push("张三");
list.push

![image.png](https://upload-images.jianshu.io/upload_images/5695517-cab5b45e05e822ca.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

![image.png](https://upload-images.jianshu.io/upload_images/5695517-87ea91033ffa8929.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

模板字符串：
![image.png](https://upload-images.jianshu.io/upload_images/5695517-ab59fcbf81d95721.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

![image.png](https://upload-images.jianshu.io/upload_images/5695517-88356ff0cd9daf2c.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

![image.png](https://upload-images.jianshu.io/upload_images/5695517-35134a86ccd6d589.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

![image.png](https://upload-images.jianshu.io/upload_images/5695517-d083bb73ed928629.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

![image.png](https://upload-images.jianshu.io/upload_images/5695517-dc610c49cc99f7fe.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

![image.png](https://upload-images.jianshu.io/upload_images/5695517-20c48e1586e66cf5.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)