es2015（es6）基础部分学习笔记（更新中...）

1 ‘use strict‘;
2 
3 if (true) {
4     let app = ‘apple‘;
5 }
6 
7 console.log(app);　　//外面是访问不到app的

1 ‘use strict‘;
2 
3 const app = ‘apple‘;
4 console.log(app);
5 
6 const app = ‘peach‘;
7 console.log(app);　　//报错，常量不能多次赋值

‘use strict‘;

function breakfast () {
    return [‘egg‘,‘bread‘,‘milk‘];
}

//传统方法
var arr = breakfast(), egg = arr[0], bread = arr[1], milk = arr[2];
console.log(egg,bread,milk);

//es6
let [t1,t2,t3] = breakfast();
console.log(t1,t2,t3);

‘use strict‘;

function breakfast () {
    return {egg:‘egg‘, milk:‘milk‘, bread:‘bread‘};
}

let {egg: a1, milk: a2, bread: a3} = breakfast();    //a1,a2,a3是自己定义的名字
console.log(a1,a2,a3);

‘use strict‘;

let food1 = ‘egg‘, food2 = ‘bread‘;

let str = `今天的早餐是 ${food1} 和 
　　　　　　${food2}`;　　//通过反斜线引号可以对字符串换行

console.log(str);

‘use strict‘;

let food1 = ‘egg‘, food2 = ‘bread‘;

let str = `今天的早餐是 ${food1} 和 
          ${food2}`;　

console.log(str.startsWith(‘今天‘),str.endsWith(‘bread‘),str.includes(‘早餐‘));　　//true true true

1 ‘use strict‘;
2 
3 function breadfast (food = ‘食物‘, drink = ‘饮料‘) {
4     console.log(`${food} ${drink}`);
5 }
6 
7 breadfast();        //输出默认值
8 breadfast(‘面包‘, ‘啤酒‘);        //输出给定值

1 ‘use strict‘;
2 
3 function breakfast (food, drink, ...others) {        //...表示后面除了前面两个参数，其余参数都放在others这个数组里
4     console.log(food, drink, others);
5     console.log(food, drink, ...others);    //将others数组里面的值展开
6 }
7 
8 breakfast(‘面包‘, ‘牛奶‘, ‘培根‘, ‘香肠‘);