All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.
Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.
elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent
| import React, { Component } from 'react'; | |
| import { createStore, combineReducers, applyMiddleware, bindActionCreators } from 'redux'; | |
| import { provide, connect } from 'react-redux'; | |
| import thunk from 'redux-thunk'; | |
| const AVAILABLE_SUBREDDITS = ['apple', 'pics']; | |
| // ------------ | |
| // reducers | |
| // ------------ |
setProps - depends on reading the last reconciled props from the current reconciled state of the app, at the time of the call. It also depends on an object that doesn't necessarily need to be there outside reconciliation. This is unlike setState, which is state that needs to be there. setState is queued up and merged at the time of reconciliation. Not at the time of the call. setState has a side-effect but is not a stateful nor mutative API.
isMounted - reads the current state of the tree, which may be stale if you're in a batch or reconciliation.
getDOMNode/findDOMNode - Reads the currently flushed node. This currently relies on the state of the system and that everything has flushed at this time. We could potentially do a forced render but that would still rely on the state of the system allowing us to synchronously being able to force a rerender of the system. Note: in 0.14, refs directly to DOM node will resolve to the DOM node. This allow you to get access to a node at the time of its choos
| // ------------ | |
| // counterStore.js | |
| // ------------ | |
| import { | |
| INCREMENT_COUNTER, | |
| DECREMENT_COUNTER | |
| } from '../constants/ActionTypes'; | |
| const initialState = { counter: 0 }; |
I fell in love with CoffeeScript a couple of years ago. Javascript has always seemed something of an interesting curiosity to me and I was happy to see the meteoric rise of Node.js, but coming from a background of Python I really preferred a cleaner syntax.
In any fast moving community it is inevitable that things will change, and so today we see a big shift toward ES6, the new version of Javascript. It incorporates a handful of the nicer features from CoffeeScript and is usable today through tools like Babel. Here are some of my thoughts and issues on moving away from CoffeeScript in favor of ES6.
While reading I suggest keeping open a tab to Babel's learning ES6 page. The examples there are great.
Holy punctuation, Batman! Say goodbye to your whitespace and hello to parenthesis, curly braces, and semicolons again. Even with the advanced ES6 syntax you'll find yourself writing a lot more punctuatio
Hi Nicholas,
I saw you tweet about JSX yesterday. It seemed like the discussion devolved pretty quickly but I wanted to share our experience over the last year. I understand your concerns. I've made similar remarks about JSX. When we started using it Planning Center, I led the charge to write React without it. I don't imagine I'd have much to say that you haven't considered but, if it's helpful, here's a pattern that changed my opinion:
The idea that "React is the V in MVC" is disingenuous. It's a good pitch but, for many of us, it feels like in invitation to repeat our history of coupled views. In practice, React is the V and the C. Dan Abramov describes the division as Smart and Dumb Components. At our office, we call them stateless and container components (view-controllers if we're Flux). The idea is pretty simple: components can't
| import { Component } from "React"; | |
| export var Enhance = ComposedComponent => class extends Component { | |
| constructor() { | |
| this.state = { data: null }; | |
| } | |
| componentDidMount() { | |
| this.setState({ data: 'Hello' }); | |
| } | |
| render() { |
| // ES7, async/await | |
| function sleep(ms = 0) { | |
| return new Promise(r => setTimeout(r, ms)); | |
| } | |
| (async () => { | |
| console.log('a'); | |
| await sleep(1000); | |
| console.log('b'); | |
| })() |
