Arrow functions provide a lexical this. It uses the this that is available at the time the function is evaluated. It is logically equivalent to (the following isn’t valid code since you can’t have a variable named this): (function(this){ // code that uses “this” })(this) In your 1st example the arrow function is within the … Read more
There are no (significant) differences. Well, okay, that’s a little premature. There are three tiny differences unique to arrow functions. Arrow functions cannot be used with new. This means, of course, that they do not have a prototype property and cannot be used to create an object with the classically-inspired syntax. new (() => {}) … Read more
I do this exact thing using async/await in my games code here Assuming req.isLoggedIn() returns a boolean, it’s as simple as: const isLoggedIn = await req.isLoggedIn(); if (isLoggedIn) { // do login stuff } Or shorthand it to: if (await req.isLoggedIn()) { // do stuff } Make sure you have that inside an async function … Read more
React v16 has just released a couple of hours ago (Yay!!) which officially supports Portal. What is Portal? Since How long has it been there? Portals provide a first-class way to render children into a DOM node that exists outside the DOM hierarchy of the parent component. Portal is not new concept in the react … Read more
Since Babel 6 use babel-register hook to make on-the-fly transpilation. First: npm install babel-register Then require it with: require(‘babel-register’); // not using // require(‘babel/register’); // or // require(‘babel-core/register); To Convert your Ecmascript 6 code to ecmascript 5, you must set Babel presets option with require babel-register Like this: require(‘babel-register’)({ presets: [ ‘es2015’ ] }); Unlike … Read more
The difference between let and const is that once you bind a value/object to a variable using const, you can’t reassign to that variable. In other words Example: const something = {}; something = 10; // Error. let somethingElse = {}; somethingElse = 1000; // This is fine. The question details claim that this is … Read more
Allen Wirfs-Brock has replied on the es-discuss list with the objections that prevented the TC39 consensus on the obj.foo = function() { } form: …for cache[getUserSecret(user)] = function() {}; it would leak the secret user info as the value of name and for obj[someSymbol] = function() {} it would leak the Symbol value as the … Read more
According to this Github page the shims include all monkey-patches that faithfully represent the ES5 features. In other words: you can use the features provided by these files as if you were using ES5 proper. The shams, however contain those features that can not be emulated with other code. They basically provide the API, so … Read more
For the specific case of classes, it is either example will work. The key thing is that it breaks down like this: import type … from imports a Flow type import … from imports a standard JS value, and the type of that value. A JS class produces a value, but Flowtype also interprets a … Read more
I think this could also have something to do with the unexpected behaviour that you might run into from implicitly giving a lexical name to what you may expect to be an anonymous function. Say for example someone understood the arrow function: (x) => x+2; To have the regular function equivalent: function(x) { return x+2; … Read more