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6.3.0 • Public • Published

Ember CLI HTMLBars

Build Status


  • Ember.js v3.8 or above
  • Ember CLI v3.8 or above
  • Node.js v12 or above

Tagged Template Usage / Migrating from htmlbars-inline-precompile

Starting with version 4.0, this addon now includes the testing helper from ember-cli-htmlbars-inline-precompile

This will require an update to the imports of the hbs helper in your tests:

Prior syntax:

import hbs from 'htmlbars-inline-precompile';


await render(hbs`
  <MyComponent />

New syntax:

import { hbs } from 'ember-cli-htmlbars';


await render(hbs`
  <MyComponent />

There is a codemod available to automate this change.

Additional Trees

For addons which want additional customizations, they are able to interact with this addon directly.

interface EmberCLIHTMLBars {
    Supports easier transpilation of non-standard input paths (e.g. to transpile
    a non-addon NPM dependency) while still leveraging the logic within
    ember-cli-htmlbars for transpiling (e.g. custom AST transforms, colocation, etc).
  transpileTree(inputTree: BroccoliTree): BroccoliTree;

transpileTree usage

// find the ember-cli-htmlbars addon
let htmlbarsAddon = this.addons.find(addon => addon.name === 'ember-cli-htmlbars');

// invoke .transpileTree passing in the custom input tree
let transpiledCustomTree = htmlbarsAddon.transpileTree(someCustomTree);

Adding Custom Plugins

You can add custom plugins to be used during transpilation of the addon/ or addon-test-support/ trees of your addon (or the app/ and tests/ trees of an application) by registering a custom AST transform.

var SomeTransform = require('./some-path/transform');

module.exports = {
  name: 'my-addon-name',

  included: function() {
    // we have to wrap these in an object so the ember-cli
    // registry doesn't try to call `new` on them (new is actually
    // called within htmlbars when compiling a given template).
    this.app.registry.add('htmlbars-ast-plugin', {
      name: 'some-transform',
      plugin: SomeTransform
    this._super.included.apply(this, arguments);

Options for registering a plugin

  • name - String. The name of the AST transform for debugging purposes.
  • plugin - A function of type ASTPluginBuilder.
  • dependencyInvalidation - Boolean. A flag that indicates the AST Plugin may, on a per-template basis, depend on other files that affect its output.
  • cacheKey - function that returns any JSON-compatible value - The value returned is used to invalidate the persistent cache across restarts, usually in the case of a dependency or configuration change.
  • baseDir - () => string. A function that returns the directory on disk of the npm module for the plugin. If provided, a basic cache invalidation is performed if any of the dependencies change (e.g. due to a npm install/upgrade).

Implementing Dependency Invalidation in an AST Plugin

Plugins that set the dependencyInvalidation option to true can provide function for the plugin of type ASTDependencyPlugin as given below.

Note: the plugin function is invoked without a value for this in context.

import {ASTPluginBuilder, ASTPlugin} from "@glimmer/syntax/dist/types/lib/parser/tokenizer-event-handlers";

export type ASTDependencyPlugin = ASTPluginWithDepsBuilder | ASTPluginBuilderWithDeps;

export interface ASTPluginWithDepsBuilder {
  (env: ASTPluginEnvironment): ASTPluginWithDeps;

export interface ASTPluginBuilderWithDeps extends ASTPluginBuilder {
   * @see {ASTPluginWithDeps.dependencies} below.
  dependencies(relativePath): string[];

export interface ASTPluginWithDeps extends ASTPlugin {
   * If this method exists, it is called with the relative path to the current
   * file just before processing starts. Use this method to reset the
   * dependency tracking state associated with the file.
  resetDependencies?(relativePath: string): void;
   * This method is called just as the template finishes being processed.
   * @param relativePath {string} A relative path to the file that may have dependencies.
   * @return {string[]} paths to files that are a dependency for the given
   * file. Any relative paths returned by this method are taken to be relative
   * to the file that was processed.
  dependencies(relativePath: string): string[];

Precompile HTMLBars template strings within other addons

module.exports = {
  name: 'my-addon-name',

  setupPreprocessorRegistry: function(type, registry) {
    var htmlbarsPlugin = registry.load('template').find(function(plugin) {
      return plugin.name === 'ember-cli-htmlbars';

    // precompile any htmlbars template string via the precompile method on the
    // ember-cli-htmlbars plugin wrapper; `precompiled` will be a string of the
    // form:
    //   Ember.HTMLBars.template(function() {...})
    var precompiled = htmlbarsPlugin.precompile("{{my-component}}");

Custom Template Compiler

You can still provide a custom path to the template compiler (e.g. to test custom template compiler tweaks in an application) by:

// ember-cli-build.js

module.exports = function(defaults) {
  let app = new EmberApp(defaults, {
    'ember-cli-htmlbars': {
      templateCompilerPath: `some_path/to/ember-template-compiler.js`,

Using as a Broccoli Plugin

var HtmlbarsCompiler = require('ember-cli-htmlbars');

var templateTree = new HtmlbarsCompiler('app/templates', {
  isHTMLBars: true,

  // provide the templateCompiler that is paired with your Ember version
  templateCompiler: require('./bower_components/ember/ember-template-compiler')



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