ECMAScript（十三）export和import

Export和import模块

Export命令用于规定模块的对外接口
import命令用于输入其他模块提供的功能

//test1.js
export let a = '你好呀';
let b = '我很好';

export function add() {
    console.log('我是加法');
}

function study() {
    console.log('我在学习');
}


export { b, study };

//test.js
import { a, b, add, study as stu } from './test1.js';

console.log(a);
console.log(b);
add();
stu();

如果出现以下错误

出现“SyntaxError: Cannot use import statement outside a module”

1、 npm init -y
2、 在 package.json 中添加字段 type

{
    "name": "test",
    "version": "1.0.0",
    "description": "",
    "main": "test.js",
    "type": "module",
    "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1"
    },
    "keywords": [],
    "author": "",
    "license": "ISC"
}