ES6 shorthand import

Question

Is there a shorter ES6 way of doing:

var assert = require('chai').assert;

than

import chai from 'chai';
var assert = chai.assert;

(chai is the chai-assertion library, in case you haven't heard of it yet.)

Wyeth

Answer 1

Yes, you can do it like:

import { assert } from 'chai';

assert must be exporting from chai in that case. See spec here and about es6 modules here

Huoh

How do you make it work? Node doesn't understand es6 by default :( – Watercraft

@Watercraft use transpilers (for example babel with require hook babeljs.io/docs/usage/require). BTW Node (v8 more precisely) supports a lot of es6 features already – Huoh

If using mocha use "mocha --compilers <path to ts-node and register like node_modules/ts-node/register> name of filename.ts" after npm install ts-node – Trait

I know this is an old post but for anyone searching - as of node v13 or higher you can put { "type": "module" } in your package.json to use ES6 import instead of babel or the experimental flags. – Deflect

Kind of pointless as chai doesn't export assert like that. This answer will NOT work for chai (at least not in version 8). – Spring

Answer 2

You can use it like this:

import * as chai from 'chai';

let assert = chai.assert;
let should = chai.should();
let expect = chai.expect;

Vital

Answer 3

I'd rather:

import {assert, should, expect}  from 'chai';

Linebreeding

It doesn't work for should: chaijs.com/guide/styles/#using-should-in-es2015 With your solution you'll have to use should().not.equal instead of should.not.equal – Gnosis

yeap, you just do: should('value1').not.be.equal('value2) – Linebreeding

or expect('someValue').to.be.ok – Linebreeding

Answer 4

I use:

import chai from 'chai';
const { assert } = chai;

Sheave