Raw MobX performance without being restrained by a Virtual DOM
This library is a demonstration of how MobX fine grain control can be leveraged directly in JSX for considerably better performance than pairing it with a Virtual DOM library. Even the fastest Virtual DOM library will have overhead when reconciling many small discreet changes into a scheduled render and patch.
Check out MobX JSX performance near the top of the charts on the JS Frameworks Benchmark.
It accomplishes this with using Babel Plugin JSX DOM Expressions. It compiles JSX to DOM statements and wraps expressions in functions that can be called by the library of choice. In this case
autorunwraps these expressions ensuring the view stays up to date. Unlike Virtual DOM only the changed nodes are affected and the whole tree is not re-rendered over and over.
To use call render as follow
import { render } from 'mobx-jsx';render(App, document.getElementById('main'));
And include 'babel-plugin-jsx-dom-expressions' in your babelrc, webpack babel loader, or rollup babel plugin.
"plugins": [["babel-plugin-jsx-dom-expressions", {moduleName: 'mobx-jsx'}]]
See plugin options
> npm install mobx-jsx babel-plugin-jsx-dom-expressions
MobX JSX works both with function and Class components (extend Component from this library).
Ships a specialize map function for optimal list rendering that takes an observable array as it's first argument. To avoid re-rendering the complete list on changes.
import { map } from "mobx-jsx";const list = observable(["Alpha", "Beta", "Gamma"]);
Unlike React
renderonly runs once, so you may not need to split in functions or methods your Lifecycles, all the initialization code could be set on
render. See the issue Lifecycles for furter information
However, you may emulate
componentDidMountand
componentWillUnmount. The microtak
Promiseresolution will be after mount and
cleanupruns at the beginning of re-evaluation so the elements aren't removed yet.
import { render, cleanup, Component as _Component } from 'mobx-jsx'class Component extends _Component { constructor(props) { super(props) if (this.componentDidMount) { Promise.resolve().then(() => this.componentDidMount()) } if (this.componentWillUnmount) { cleanup(() => this.componentWillUnmount()) } } }
class App extends Component { componentDidMount(){ console.log('componentDidMount')}
componentWillUnmount(){ console.log('componentWillUnmount') } }
import { render, lazy } from "mobx-jsx";// use lazy to allow code splitting const SomeComponent = lazy(() => import("./SomeComponent"));
function App() { return ( <> > ); }
render(App, document.body);
Alternatively supports Tagged Template Literals or HyperScript for non-precompiled environments by installing the companion library and including variants:
js import { html } from 'mobx-jsx/html'; // or import { h } from 'mobx-jsx/h';There is a small performance overhead of using these runtimes but the performance is still very impressive. Tagged Template solution is much more performant that the HyperScript version, but HyperScript opens up compatibility with some companion tooling like:
Further documentation available at: Lit DOM Expressions and Hyper DOM Expressions.