Why you shouldn’t use inline arrow functions in JSX props Using arrow functions or binding in JSX is a bad practice that hurts performance, because the function is recreated on each render. Whenever a function is created, the previous function is garbage collected. Rerendering many elements might create jank in animations. Using an inline arrow … Read more
Try defaulting the exports in your components: import React from ‘react’; import Navbar from ‘react-bootstrap/lib/Navbar’; export default class MyNavbar extends React.Component { render(){ return ( <Navbar className=”navbar-dark” fluid> … </Navbar> ); } } by using default you express that’s going to be member in that module which would be imported if no specific member name … Read more
console.log(‘last’, [1, 3, 4, 5].slice(-1)); console.log(‘second_to_last’, [1, 3, 4, 5].slice(-2));
defaultProps on functional components will eventually be deprecated (as per Dan Abramov, one of the core team), so for future-proofing it’s worth using default parameters.
=== is called strict comparison operator in JavaScript. Object.is and strict comparison operator behave exactly the same except for NaN and +0/-0. From MDN: Object.is() method is not the same as being equal according to the === operator. The === operator (and the == operator as well) treats the number values -0 and +0 as … Read more
It’s a destructuring assignment. Specifically, an object destructuring assignment. It might help to see it rewritten in a more verbose way. const abc = Object.abc; const def = Object.def; It’s a shorthand way to initialise variables from object properties. const name = app.name; const version = app.version; const type = app.type; // Can be rewritten … Read more
There are no private, public or protected keywords in current ECMAScript 6 specification. So Traceur does not support private and public. 6to5 (currently it’s called “Babel”) realizes this proposal for experimental purpose (see also this discussion). But it’s just proposal, after all. So for now you can just simulate private properties through WeakMap (see here). … Read more
For me it happened when I forgot to write extends React.Component at the end. I know it’s not exactly what YOU had, but others reading this answer can benefit from this, hopefully.
According to the ES2015 grammar, a property on an object literal can only be one of three things: PropertyDefinition: IdentifierReference PropertyName : AssignmentExpression MethodDefinition The only one of these type that allows a leading get is MethodDefinition: MethodDefinition : PropertyName ( StrictFormalParameters ) { FunctionBody } GeneratorMethod get PropertyName ( ) { FunctionBody } set … Read more
index.js import {$,jQuery} from ‘jquery’; // export for others scripts to use window.$ = $; window.jQuery = jQuery; First, as @nem suggested in comment, the import should be done from node_modules/: Well, importing from dist/ doesn’t make sense since that is your distribution folder with production ready app. Building your app should take what’s inside … Read more