5.ES6模块导出导入

导出变量和函数calc.js

export const name = 'calc';

export const add = (x, y) => {
    return x + y;
};

export const subtract = (x, y) => {
    return x - y;
};

导入变量和函数，并加以使用

import * as calc from './calc';

const x = 3;
const y = 5;

console.log(`${calc.name}`);

const result_add = calc.add(x, y);
console.log(`${x} + ${y} = ${result_add}`);

const result_subtract = calc.subtract(x, y);
console.log(`${x} - ${y} = ${result_subtract}`);

另一种导入方法

import {name, add, subtract} from './calc';

const x = 3;
const y = 5;

console.log(`${name}`);

const result_add = add(x, y);
console.log(`${x} + ${y} = ${result_add}`);

const result_subtract = subtract(x, y);
console.log(`${x} - ${y} = ${result_subtract}`);

默认导出（多个函数或变量只能导出一个默认的）calc.js

export const name = 'calc';

const add = (x, y) => {
    return x + y;
};

export const subtract = (x, y) => {
    return x - y;
};

export { add as default };

导入并使用

import adds,{name,subtract} from './calc';

const x = 3;
const y = 5;

console.log(`${name}`);

const result_add = adds(x, y);
console.log(`${x} + ${y} = ${result_add}`);

const result_subtract = subtract(x, y);
console.log(`${x} - ${y} = ${result_subtract}`);

默认导出一个对象

export default {
    name: 'calc',
    add: (x, y) => {
        return x + y;
    },
    subtract: (x, y) => {
        return x - y;
    }
};

导入并使用

import calc from './calc';

const x = 3;
const y = 5;

console.log(`${calc.name}`);

const result_add = calc.add(x, y);
console.log(`${x} + ${y} = ${result_add}`);

const result_subtract = calc.subtract(x, y);
console.log(`${x} - ${y} = ${result_subtract}`);

导出一个类

export default class Calc {
    constructor (x, y) {
        this.x = x;
        this.y = y;
    }

    add () {
        return this.x + this.y;
    }

    subtract () {
        return this.x - this.y;
    }

}

导入并使用

import Calc from './calc';

const x = 3;
const y = 5;
const calc = new Calc(x, y);

const result_add = calc.add();
console.log(`${x} + ${y} = ${result_add}`);

const result_subtract = calc.subtract();
console.log(`${x} - ${y} = ${result_subtract}`);