You will be able to do a shallow merge/extend/assign in ES6 by using Object.assign: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign Syntax: Object.assign(target, sources); where …sources represents the source object(s). Example: var obj1 = {name: ‘Daisy’, age: 30}; var obj2 = {name: ‘Casey’}; Object.assign(obj1, obj2); console.log(obj1.name === ‘Casey’ && obj1.age === 30); // true
The reason why this style can be used (and possibly why it was used here) is that _ is one character shorter than (). Optional parentheses fall into the same style issue as optional curly brackets. This is a matter of taste and code style for the most part, but verbosity is favoured here because … Read more
From my answer to another question, this can be simpler: The only requirement is to configure your test environment to Babel, and add the ECMAScript 6 transform plugin: Step 1: Add your test environment to .babelrc in the root of your project: { “env”: { “test”: { “plugins”: [“@babel/plugin-transform-modules-commonjs”] } } } Step 2: Install the … Read more
In Chrome, most of the ES6 features are hidden behind a flag called “Experimental JavaScript features”. Visit chrome://flags/#enable-javascript-harmony, enable this flag, restart Chrome and you will get many new features. Arrow functions are not yet implemented in V8/Chrome, so this flag won’t “unlock” arrow functions. Since arrow functions are a syntax change, it is not … Read more
Simply const obj = {}; for (const key of yourArray) { obj[key] = whatever; } or if you prefer “functional” style: const obj = yourArray.reduce((o, key) => Object.assign(o, {[key]: whatever}), {}); using the modern object spread operator: const obj = yourArray.reduce((o, key) => ({ …o, [key]: whatever}), {}) Example: [ { id: 10, color: “red” … Read more
Features without –harmony flag: “for-of” loop Map, Set, WeakMap, WeakSet (already specified in question) Symbol (already specified in question) Promise (already specified in question) Array methods: .keys() .values() .entries() [Symbol.iterator] Object: .observe() (initially was planned for ES7, but was removed from the spec entirely on November 2, 2015) .is() .setPrototypeOf() .getOwnPropertySymbols() .getNotifier() (not es6, example … Read more
Is it possible to export Arrow functions in ES6/7? Yes. export doesn’t care about the value you want to export. The export statement below gives a syntax error … why? You cannot have a default export and give it a name (“default” is already the name of the export). Either do export default () => … Read more
It’s the new ES2015 (the EcmaScript spec formally known as ES6) computed property name syntax. It’s a shorthand for the someObject[someKey] assignment that you know from ES3/5: var a = “b” var c = {[a]: “d”} is syntactic sugar for: var a = “b” var c = {} c[a] = “d”
The pattern I have seen so far is to keep the es6 files in a src directory and build your stuff in npm’s prepublish to the lib directory. You will need an .npmignore file, similar to .gitignore but ignoring src instead of lib.
Yes there is, check out Array.prototype.entries(). const foobar = [‘A’, ‘B’, ‘C’]; for (const [index, element] of foobar.entries()) { console.log(index, element); }