inferno

A framework for building lightning fast user interfaces

Inferno

Inferno is an isomorphic library for building user interfaces with high performance (crucial when targeting mobile devices). Unlike typical virtual DOM libraries like React, Mithril, Cycle and Om, Inferno does not rely on diffing DOM virtual elements, but instead it differentiates static content from dynamic content and only diffs the values that change within a given fragment of virtual DOM elements (we call them virtual fragments).

In addition to this, we've painstakingly optimized the code to ensure there is as little overhead as possible. We believe that Inferno is currently the fastest virtual DOM implementation on out there - as shown by some of our benchmarks. Inferno is all about performance, whilst keeping a robust API that replicates the best features from libraries such as React. If you'd like to know more about how Inferno works under-the-hood, check out the how Inferno works document.

In principle, Inferno is compatible with the standard React API, allowing for painless transition from React to Inferno in most use cases. Furthermore, Inferno has a Babel plugin allowing JSX syntax to transpile to optimised Inferno templates.

  • one of the fastest front-end libraries for rendering UI in the DOM
  • components have a similar API to React ES2015 components with inferno-component
  • stateless components are fully supported and have more usability thanks to Inferno's hooks system
  • isomorphic/universal for easy server-side rendering with inferno-server

Very much like React, Inferno requires the inferno and the inferno-dom packages for consumption in the browser's DOM. Inferno also has the inferno-server package for server-side rendering of fragments to HTML strings (differing from React's route of using react-dom/server for server-side rendering). Furthermore, rather than include the ES2015 component with class syntax in core (like React), it's in a separate package inferno-component to allow for better modularity.

NPM:

Core package:

npm install --save inferno

ES2015 stateful components (with lifecycle events) package:

npm install --save inferno-component 

Browser DOM rendering package:

npm install --save inferno-dom 

Server-side rendering package:

npm install --save inferno-server 

Pre-bundled files for browser consumption:

http://infernojs.org/releases/0.5.22/inferno.min.js
http://infernojs.org/releases/0.5.22/inferno-component.min.js
http://infernojs.org/releases/0.5.22/inferno-dom.min.js
http://infernojs.org/releases/0.5.22/inferno-server.min.js

Let's start with some code. As you can see, Inferno intentionally keeps the same good (in our opinion) design ideas regarding components, one-way data passing and separation of concerns. In these examples, JSX is used via the Inferno JSX Babel Plugin to provide a very easy way to express virtual fragments.

import Inferno from 'inferno';
import InfernoDOM from 'inferno-dom';
 
const message = "Hello world";
 
InfernoDOM.render(
  <MyComponent message={ message } />,
  document.getElementById("app")
)

Furthermore, Inferno also uses ES6 components like React:

import { Component } from `inferno-component`;
 
class MyComponent extends Component {
  constructor(props) {
    super(props);
    this.state = {
      counter: 0
    }
  }
  render() {
    return (
      <div>
        <h1>Header!</h1>
        <span>Counter is at: { this.state.counter }</span>
      </div>
    )
  }
}
 
InfernoDOM.render(<MyComponent />, document.body);

The real difference between React and Inferno is the performance offered at run-time. Inferno can handle large, complex DOM models without breaking a sweat. This is essential for low-power devices such as tablets and phones, where users of those devices are quickly demanding desktop like performance on their slower hardware.

const template = Inferno.createTemplate(() => ({
  tag: 'div',
  attrs: { className: 'test'},
  children: [
    'This', ' is ', 'a test!'
  ]
}));
 
InfernoDOM.render(template(), document.body);
import { Component } from 'inferno-component';
 
const { createElement } = Inferno.TemplateFactory;
 
class BasicComponent extends Component {
    render() {
        const template = Inferno.createTemplate((name, title) =>
            createElement('div', {
                    className: 'basic'
                },
                createElement('span', {
                    className: name
                }, 'The title is ', title)
            )
        );
        return template(this.props.name, this.props.title);
    }
}
 
const template = Inferno.createTemplate((Component, title) =>
    createElement('div', null,
        createElement(Component, {
            title: title,
            name: 'basic-render'
        })
    )
);
 
InfernoDOM.render(template(BasicComponent, 'abc'), container);

Inferno.TemplateFactory provides a factory createElement() function that can be used to build up virtual DOM structures in a similar sense to how React.creactElement() works. It's first argument is the node, second argument is the attributes and all remaining arguments are it's children.

Stateful component:

import { Component } from 'inferno-component';
 
class MyComponent extends Component {
  render() {
    ...
  }
}

This is the base class for Inferno Components when they're defined using ES6 classes.

Stateless component:

const MyComponent => ({ name, age }) => 
  <span>My name is: { name } and my age is: {age}</span>  
);

Stateless components are first-class functions where their first argument is the props passed through from their parent.

import InfernoDOM from 'inferno-dom';
 
const divRef = InfernoDOM.createRef();
 
InfernoDOM.render(<div ref={ divRef } />, document.body);
divRef.element.textContent = 'Modifying the DOM node directly!';

Creates a mutable object that links an Inferno rendered template node to its real DOM node upon being mounted to the DOM.

import InfernoDOM from 'inferno-dom';
 
InfernoDOM.render(<div />, document.body);

Render a fragment into the DOM in the supplied container given the supplied template. If the fragment was previously rendered into container, this will perform an update on it and only mutate the DOM as necessary to reflect the latest Inferno fragment.

import InfernoServer from 'inferno-server';
 
InfernoServer.renderToString(<div />, document.body);

Render a fragment into the HTML string given the supplied template.

Please note: hooks are provided by inferno-dom;

Inferno supports many of the basic events upon DOM nodes, such as onClick, onMouseOver and onTouchStart. Furthermore, Inferno allows you to attach common hooks directly onto components and DOM nodes. Below is the table of all possible hooks available in inferno-dom.

Name Triggered when Arguments to callback
onCreated a DOM node has just been created domNode
onAttached a DOM node being attached to the document domNode
onWillDetach a DOM node is about to be removed from the document domNode
onWillUpdate a DOM node is about to perform any potential updates domNode
onDidUpdate a DOM node has performed any potential updates domNode
onComponentWillMount a stateless component is about to mount domNode, props
onComponentDidMount a stateless component has mounted successfully domNode, props
onComponentWillUnmount a stateless component is about to be unmounted domNode, props
onComponentShouldUpdate a stateless component has been triggered to updated domNode, lastProps, nextProps
onComponentWillUpdate a stateless component is about to perform an update domNode, lastProps, nextProps
onComponentDidUpdate a stateless component has performed an updated domNode, props

It's simple to implicitly assign hooks to both DOM nodes and stateless components. Please note: stateful components (ES2015 classes) from inferno-component do not support hooks.

function createdCallback(domNode, props) {
    // [domNode] will be available for DOM nodes and components (if the component has mounted to the DOM)
// [props] will only be passed for stateless components
}
 
InfernoDOM.render(<div onCreated={ createdCallback } />, document.body);
 
function StatelessComponent({ props }) {
return <div>Hello world</div>;
}
 
InfernoDOM.render(<StatelessComponent onComponentWillMount={ createdCallback } />, document.body);

Hooks provide powerful lifecycle events to stateless components, allowing you to build components without being forced to use ES2015 classes.

Inferno tries to address two problems with creating UI components:

  • Writing large applications in large teams is slow in terms of development and expensive in costs – it shouldn't be.
  • Writing complex applications generally gives poor performance on mobile/tablet/older machines – it shouldn't.
  • Writing intensive modern UIs that require many updates/animations falls apart and becomes overly complicated - it shouldn't be.

Writing code should be fun. Browsers are getting more advanced and the technologies being supported are growing by the week. It's about time a library offered more fun without compromising performance.

Inferno has it's own JSX Babel plugin.