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Try “asm-dom” that is virtual DOM library by using WebAssembly

kwbtsts profile image kwst ・3 min read

What is “asm-dom”?

https://github.com/mbasso/asm-dom
asm-dom is a virtual DOM library using WebAssembly. Its “diff” and “patch” algorithm of virtual DOM are implemented by WebAssembly and it’s a minimal implementation so it doesn’t have high function as React. I expect it is very fast by WebAssembly.

The date of the initial commit is 2017/2/26 so it’s a year old.
Copyright and Lisense includes the name of “snabbdom”. It maybe related to snabbdom.

Simon Friis Vindum, 2015 as part of project snabbdom

Usage

It can be written by C++ but I used JS like WEB in this time.

npm i --save asm-dom
npm i -D arraybuffer-loader

I added webpack and webpack-dev-server to bundle by webpack.

npm i -D webpack webpack-dev-server

webpack.config is like this. I added arraybuffer-loader to load .wasm file. I refer to the document for JS.

var resolve = require('path').resolve;

module.exports = env => {
  const dist = env.prod ? 'docs' : 'dist';
  return {
    entry: './src/index.js',
    output: {
      filename: 'bundle.js',
      path: resolve(__dirname, dist),
      pathinfo: !env.prod,
    },
    node: {
      fs: 'empty'
    },
    devtool: env.prod ? 'source-map' : 'eval',
    devServer: {
      contentBase: resolve(__dirname, dist),
      historyApiFallback: true,
      compress: true,
      port: 9000
    },
    module: {
      loaders: [
        {
          test: /\.wasm$/,
          loaders: ['arraybuffer-loader']
        }
      ]
    }
  };
}

VS "virtual-dom"

I compared speed of "asm-dom" with "virtual-dom" that is a virtual DOM library. I measured the time of replacing 30000 text elements of <div>. I used Chrome ver61.

"asm-dom" won

"asm-dom" is 2 times faster than "virtual-dom". I never imagined this result. WebAssembly is awesome. I would like to compare also only "diff" and "patch" algorithm of React.

asm-dom result
asm-dom result

virtual-dom result
virtual-dom result

The code for measuring

I uploaded the code into this.
You can define DOM like hyperscript so make nodes by h() and apply diff by patch() like as virtual-dom.

asm-dom code

import init from 'asm-dom';

init().then(asmDom => {
  const { h, patch } = asmDom;

  const root = document.getElementById('root');

  let vnode = h('div', {}, []);
  patch(root, vnode);

  let cnt = 0;
  const id = setInterval(() => {
    console.time('apply patch in 30000 elements');
    const list = [];
    for (let i = 0; i < 30000; i++) {
      list.push(
        h('div', {}, [ Math.random() + '' ])
      );
    }
    const newVnode = h('div', {}, list);
    patch(vnode, newVnode);
    vnode = newVnode;
    console.timeEnd('apply patch in 30000 elements');
    cnt++;
    if (cnt >= 10) {
      clearInterval(id);
    }
  }, 100);
});

virtual-dom code

const h = require('virtual-dom/h');
const diff = require('virtual-dom/diff');
const patch = require('virtual-dom/patch');
const createElement = require('virtual-dom/create-element');

let cnt = 0;
let tree = h('div', {}, []);
let rootNode = createElement(tree);
document.body.appendChild(rootNode);

const id = setInterval(function () {
  console.time('apply patch in 30000 elements');
  const list = [];
  for (let i = 0; i < 30000; i++) {
    list.push(
    h('div', {}, [ Math.random() + '' ])
    );
  }
  const newTree = h('div', {}, list);
  const patches = diff(tree, newTree);
  rootNode = patch(rootNode, patches);
  tree = newTree;
  console.timeEnd('apply patch in 30000 elements');
  cnt++;
  if (cnt >= 10) {
    clearInterval(id);
  }
}, 1000);

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