The return value will always be a promise. If you don’t explicitly return a promise, the value you return will automatically be wrapped in a promise. async function increment(num) { return num + 1; } // Even though you returned a number, the value is // automatically wrapped in a promise, so we call // … Read more
One possible way: const result = doSomething(), { a, b } = result; You still have to duplicate the name, though. const token isn’t quite right-handy. )
Object rest spread is stage 3 proposal and not a part of any spec (will probably be included in ES2018). More importantly, export has syntax that mimics existing JS syntax but doesn’t interpret { … } as an expression. export syntax was strictly defined because ES2015 modules are supposed to be statically analyzed. This is … Read more
To expand upon what Patrick Roberts said, you cannot do what you are asking, but you can do something like this instead: class MyClass { constructor() { //static initialization } async initialize() { await WhatEverYouWant(); } static async create() { const o = new MyClass(); await o.initialize(); return o; } } Then in your code … Read more
You are looking for var obj = Object.assign({}, …array) that creates a new object instead of mutating array[0].
You can assign destructured values not only to variables but also to existing objects: const arr = [1,2,3], o = {}; ({0:o.one, 1:o.two, 2:o.three} = arr); This works without any additional variables and is less repetitive. However, it also requires two steps, if you are very particular about it.
node 10 and newer Since Node.js v10.0, there is assert.rejects which does just that. Older versions of node async functions never throw – they return promises that might be rejected. You cannot use assert.throws with them. You need to write your own asynchronous assertion: async function assertThrowsAsynchronously(test, error) { try { await test(); } catch(e) … Read more
In fact, it’s exactly the same in terms of performance. React.JS is a relatively new technology, so it’s not clear yet what are considered good practices or don’t. If you want to trust someone, check this AirBNB’s styleguide: https://github.com/airbnb/javascript/tree/master/react#ordering import React, { PropTypes } from ‘react’; const propTypes = { id: PropTypes.number.isRequired, url: PropTypes.string.isRequired, text: … Read more
You can use object spread to have an optional property: let flag1 = true; let flag2 = false; // extra cases added by Abdull let optionalKey8 = 8; let optionalKey9 = undefined; let optionalKey10 = false; let optionalKey11 = null; let optionalKey12 = “twelve”; const obj = { requiredKey1: 1, requiredKey2: 2, …(flag1 && { … Read more
You can use the object rest/spread syntax: // We destructure our “this.props” creating a ‘styles’ variable and // using the object rest syntax we put the rest of the properties available // from “this.props” into a variable called ‘otherProps’ const { styles, …otherProps } = this.props; const section = cloneElement(this.props.children, { className: styles.section, // We … Read more