Dealing with unhandled rejected native promises (and async/await uses native promises) is a feature supported now in V8. It’s used in the latest Chrome to output debugging information when a rejected promise is unhandled; try the following at the Babel REPL: async function executor() { console.log(“execute”); } async function doStuff() { console.log(“do stuff”); throw new … Read more
Because it’s not supported in IE, it is not supported also in Opera (see the compatibility table), but you can use the suggested polyfill: Polyfill This method has been added to the ECMAScript 2015 specification and may not be available in all JavaScript implementations yet. However, you can easily polyfill this method: if (!String.prototype.includes) { … Read more
With JavaScript now being updated each year (ES2015, ES2016, ES2017, etc.), how does Microsoft plan to keep IE 11 up to date? They’re not going to. As of 2015, Internet Explorer 11 will no longer be receiving any new features or platform bug fixes. Only security updates will be provided to IE11 from here on … Read more
How I proceed: install globally eslint : npm install -g eslint install babel-eslint : npm install –save-dev babel-eslint install eslint-plugin-react : npm install –save-dev eslint-plugin-react create .eslintrc file in you root directory. here is my config: { “env”: { “browser”: true, “node”: true, “es6”: true, “jest”: true, “jquery”: true }, “parser”: “babel-eslint”, “parserOptions”: { “ecmaVersion”: … Read more
Update: The create-react-app polyfill approach and docs have changed since this question/answer. You should now include react-app-polyfill (here) if you want to support older browsers like ie11. However, this only includes the “…minimum requirements and commonly used language features“, so you’ll still want to use one of the approaches below for less common ES6/7 features … Read more
tl;dr: NaN is treated differently: [NaN].indexOf(NaN) > -1 is false [NaN].includes(NaN) is true From the proposal: Motivation When using ECMAScript arrays, it is commonly desired to determine if the array includes an element. The prevailing pattern for this is if (arr.indexOf(el) !== -1) { … } with various other possibilities, e.g. arr.indexOf(el) >= 0, or … Read more
You have to pass a promise to await. Convert the observable’s next event to a promise and await that. if (condition) { await observable.first().toPromise(); } Edit note: This answer originally used .take(1) but was changed to use .first() which avoids the issue of the Promise never resolving if the stream ends before a value comes … Read more
If you use Babel you can use the following syntax to copy property b from x into variable b and then copy rest of properties into variable y: let x = {a: 1, b: 2, c: 3, z:26}; let {b, …y} = x; and it will be transpiled into: “use strict”; function _objectWithoutProperties(obj, keys) { … Read more
I think you’re looking for the with statement, it does exactly what you are asking for: const vegetableColors = {corn: ‘yellow’, peas: ‘green’}; with (vegetableColors) { console.log(corn);// yellow console.log(peas);// green } However, it is deprecated (in strict mode, which includes ES6 modules), for good reason. destructure all properties into the current scope You cannot in … Read more
Yes, you can do that, and it will run the two asynchronous functions in parallel. You’ve just created a promise and thrown it away. However, this means that when the promise is rejected you won’t notice. You’ll just get an unhandledRejection eventually which will crash your process if not handled. Is this OK? How can … Read more