[es6] import, export, default cheatsheet

1. Name exports

//------ lib.js ------
export const sqrt = Math.sqrt;
export function square(x) {
    return x * x;
}
export function diag(x, y) {
    return sqrt(square(x) + square(y));
}

//------ main.js ------
import { square, diag } from 'lib';
console.log(square(11)); // 121
console.log(diag(4, 3)); // 5

//------ main.js ------
import * as lib from 'lib';
console.log(lib.square(11)); // 121
console.log(lib.diag(4, 3)); // 5

2. Default exports (one per module)

//------ myFunc.js ------
export default function () { ... };

//------ main1.js ------
import myFunc from 'myFunc';
myFunc();

3. Mixed named & default exports

//------ underscore.js ------
export default function (obj) {
    ...
};
export function each(obj, iterator, context) {
    ...
}
export { each as forEach };

//------ main.js ------
import _, { each } from 'underscore';
...

4. Cyclical Dependencies

// lib.js
import Main from 'main';
var lib = {message: "This Is A Lib"};
export { lib as Lib };

// main.js
import { Lib } from 'lib';
export default class Main { 
  // ....
}