#### 变量字面量声明
---
- 必须使用关键字 var, (ES6使用 let / const ),严禁在不使用关键字时声明一个变量;
- 基础类型的声明推荐使用字面量的形式,而非构造函数形式;
- 如果一次需要声明多个变量,推荐使用一次关键字声明,英文标准逗号进行分割;
> <span class="do">正确实践:</span>
```js
//一次声明多个变量
var a = 1, b = 2, c = "hello wolrd";
//字面量形式
var student = {
name : "Jack",
age : 19,
sexy : 0
level : 2
};
var colors = ["red","yellow","pink","green"];
//ES6
let pets = {};
const greetingWords = "greeting! My friend!";
```
> <span class="dont">错误实践:</span>
```js
var a = 1;
var b = 2;
var c = "hello world";
var student = new Object();
student.name = "Jack";
student.age = 19;
var colors = new Array("red","yellow");
let pets = new Object();
const greetingWords = new String("greeting! My friend!");
```
