🐉 A simple library for composable DOM elements using tagged template strings.
Latest commit 6dab832 Dec 7, 2016 @yoshuawuyts yoshuawuyts 4.5.1
Failed to load latest commit information.
bench Add bench entry Mar 7, 2016
test xmlns svg fix (#58) Dec 7, 2016
.gitignore Init Feb 27, 2016
.travis.yml Add travis Feb 27, 2016
README.md chore(docs): add "yo-yoify" section (#49) Sep 30, 2016
bel.d.ts Add typescript definition and support Oct 22, 2016
index.js xmlns svg fix (#58) Dec 7, 2016
package.json 4.5.1 Dec 7, 2016



NPM version build status Downloads js-standard-style experimental

A simple library for composable DOM elements using tagged template strings.

If you're looking for a higher level front end framework, try yo-yo. Or even higher than that, try choo.


For a more in depth tutorial on getting started, please check out the wiki.


Please use yo-yoify which will transform any Function.caller into plain strings until an alternative solution to identify element creators is implemented.

yo-yoify can resolve the error like below:

TypeError: Function.caller used to retrieve strict caller


TypeError: access to strict mode caller function is censored

A Simple Element

Create an element:

// list.js
var bel = require('bel')

module.exports = function (items) {
  return bel`<ul>
    ${items.map(function (item) {
      return bel`<li>${item}</li>`

Then pass data to it and add to the DOM:

// app.js
var createList = require('./list.js')
var list = createList([

Data Down, Actions Up

// list.js
var bel = require('bel')

// The DOM is built by the data passed in
module.exports = function (items, onselected) {
  function render () {
    return bel`<ul>
    ${items.map(function (item) {
      return bel`<li>${button(item.id, item.label)}</li>`
  function button (id, label) {
    return bel`<button onclick=${function () {
      // Then action gets sent up
  var element = render()
  return element
// app.js
var bel = require('bel')
var morphdom = require('morphdom')
var list = require('./list.js')

module.exports = function (bears) {
  function onselected (id) {
    // When a bear is selected, rerender with the newly selected item
    // This will use DOM diffing to render, sending the data back down again
    morphdom(element, render(id))
  function render (selected) {
    return bel`<div className="app">
      <h1>Selected: ${selected}</h1>
      ${list(bears, onselected)}
  // On first render, we haven't selected anything
  var element = render('none')
  return element

lifecycle events

Use the onload and onunload properties to call a function when the element is inserted and removed from the DOM respectively.

var bel = require('bel')

var modal = bel`<div onload=${function (element) {
  console.log('Hello DOM!')
}} onunload=${function (element) {
  console.log('Goodbye DOM!')


use with/without hyperx

hyperx is built into bel but there may be times when you wish to use your own version or implementation of hyperx. Or if you prefer to create elements using bel without using tagged template literals:

var createElement = require('bel').createElement
var hyperx = require('hyperx')
var bel = hyperx(createElement)

var element = bel`<div class="heading">Hello!</div>`

// ...

var sameElement = createElement('div', { className: 'heading' }, ['Hello!'])


bel sets attributes with element.setAttribute() and element.setAttributeNS(), and creates text nodes with document.createTextNode(). These approaches mitigate some Cross-Site Scripting (XSS) attacks. You should still code carefully every time you put content from users in the DOM.

similar projects

  • vel
    minimal virtual-dom library
  • base-element
    An element authoring library for creating standalone and performant elements
  • virtual-dom
    A Virtual DOM and diffing algorithm
  • hyperscript
    Create HyperText with JavaScript.


(c) 2016 Kyle Robinson Young. MIT License