({ latitude, longitude } = props.userLocation.coords); Destructuring needs to be either after a let, const or var declaration or it needs to be in an expression context to distinguish it from a block statement.
import React, { Component, PropTypes } from ‘react’; This says: Import the default export from ‘react’ under the name React and import the named exports Component and PropTypes under the same names. This combines the two common syntaxes which you’ve probably seen import React from ‘react’; import { Component, PropTypes } from ‘react’; The first … Read more
This is how it’s intended, as described in the documentation. /** * My cool function. * * @param {Object} obj – An object. * @param {string} obj.prop1 – Property 1. * @param {string} obj.prop2 – Property 2. */ const fn = function ({prop1, prop2}) { // Do something with prop1 and prop2 } So, your … Read more
You can use Promise.all (spec, MDN) for that: It accepts a bunch of individual promises and gives you back a single promise that is resolved when all of the ones you gave it are resolved, or rejected when any of them is rejected. So if you make doSomeAsyncStuff return a promise, then: const promises = … Read more
The rules for ES2015 (ES6) classes basically come down to: In a child class constructor, this cannot be used until super is called. ES6 class constructors MUST call super if they are subclasses, or they must explicitly return some object to take the place of the one that was not initialized. This comes down to … Read more
Right from that very paragraph your linked to: Set objects must be implemented using [mechanisms] that, on average, provide access times that are sublinear on the number of elements in the collection. You will find the same sentence for Maps, WeakMaps and WeakSets. It looks the ECMA spec mandates that the implementations (e.g. Set.prototype.has) are … Read more
It is complicated; I tried a lot! In the end, this one-liner worked for my custom ES6 class instances: let clone = Object.assign(Object.create(Object.getPrototypeOf(orig)), orig) It avoids setting the prototype because they say it slows down the code a lot. It supports symbols but isn’t perfect for getters/setters and isn’t working with non-enumerable properties (see Object.assign() … Read more
Yes, your example would work fine. As for exposing your classes, you can export a class just like anything else: class Animal {…} module.exports = Animal; Or the shorter: module.exports = class Animal { }; Once imported into another module, then you can treat it as if it were defined in that file: var Animal … Read more
The super call will invoke the Function constructor, which expects a code string. If you want to access your instance data, you could just hardcode it: class Smth extends Function { constructor(x) { super(“return “+JSON.stringify(x)+”;”); } } but that’s not really satisfying. We want to use a closure. Having the returned function be a closure … Read more
Babel’s stage presets equate to the TC39 Process and the different states of each proposal for a potential language change. They include implementations and polyfills for all of the proposed changes in that stage. Anything currently in Stage-0 is Strawman, not ES6. It is future Javascript and absolutely not certain that it will ever make … Read more