gulp-handlebars

Handlebars plugin for gulp

Usage

Install gulp-handlebars as a development dependency:

npm install --save-dev gulp-handlebars

VERSION MISMATCH ERROR?!

Are you seeing this error when using pre-compliled templates?

Error: Template was precompiled with an older version of Handlebars

If you're getting a version mismatch error when using pre-compliled templates, install the handlebars version of your choice and pass it as options.handlebars, then include the appropriate runtime in your client-side application.

Here's how you install your own version of handlebars:

npm install --save handlebars@^4.0.0

And here's how you use that verison of handlebars in gulp-handlebars:

handlebars({
  handlebars: require('handlebars')
})

The runtime is located in:

node_modules/handlebars/dist/handlebars.js

Compiling templates for the browser

gulp-declare and gulp-wrap can be used to safely declare template namespaces and make templates available for use in the browser.

First, install development dependencies:

npm install --save-dev gulp-handlebars gulp-wrap gulp-declare gulp-concat

Given the following directory structure:

├── gulpfile.js              # Your gulpfile
└── source/                  # Your application's source files
    └── templates/           # A folder containing templates named with dot notation
        └── home.header.hbs  # A template that will be available as MyApp.templates.home.header

To compile all templates in source/templates/ to build/js/templates.js under the MyApp.templates namespace:

gulpfile.js

var handlebars = require('gulp-handlebars');
var wrap = require('gulp-wrap');
var declare = require('gulp-declare');
var concat = require('gulp-concat');

gulp.task('templates', function(){
  gulp.src('source/templates/*.hbs')
    .pipe(handlebars())
    .pipe(wrap('Handlebars.template(<%= contents %>)'))
    .pipe(declare({
      namespace: 'MyApp.templates',
      noRedeclare: true, // Avoid duplicate declarations
    }))
    .pipe(concat('templates.js'))
    .pipe(gulp.dest('build/js/'));
});

The template's filename is combined with the namespace, so the resulting build/js/templates.js would look like:

this["MyApp"] = this["MyApp"] || {};
this["MyApp"]["templates"] = this["MyApp"]["templates"] || {};
this["MyApp"]["templates"]["home"] = this["MyApp"]["templates"]["home"] || {};
this["MyApp"]["templates"]["home"]["header"] = Handlebars.template(function() { /* compiled template function */ });

Namespace templates according to nested directories

See the namespaceByDirectory example if you'd like to compile templates with a mapping that looks like this:

Compiling to various module systems

See the gulp-define-module documentation for details on how to define templates as AMD, Node, CommonJS, and hybrid modules.

See the amd example for a full example of compiling templates to AMD modules.

gulp-handlebars makes the following available for use in gulp-define-module's wrapper template option:

• <%= handlebars %> - The Handlebars template, wrapped in a call to Handlebars.template()
• <%= contents %> - The bare Handlebars template (not wrapped).

gulp-handlebars also sets a default options.require of { Handlebars: 'handlebars' } for gulp-define-module so Handlebars will be present in when defining AMD, Node, CommonJS, or hybrid modules. You can change this by passing a different options.require when you invoke gulp-define-module.

Compiling partials

The following example will precompile and register partials for all .hbs files in source/partials/, then store the result as build/js/partials.js;

var path = require('path');
var gulp = require('gulp');
var wrap = require('gulp-wrap');
var concat = require('gulp-concat');
var handlebars = require('gulp-handlebars');

gulp.task('partials', function() {
  // Assume all partials are in a folder such as source/partials/**/*.hbs
  gulp.src(['source/partials/**/*.hbs'])
    .pipe(handlebars())
    .pipe(wrap('Handlebars.registerPartial(<%= processPartialName(file.relative) %>, Handlebars.template(<%= contents %>));', {}, {
      imports: {
        processPartialName: function(fileName) {
          // Strip the extension and the underscore
          // Escape the output with JSON.stringify
          return JSON.stringify(path.basename(fileName, '.js'));
        }
      }
    }))
    .pipe(concat('partials.js'))
    .pipe(gulp.dest('build/js/'));
});

See the partials example for a full example that compiles partials and templates down to a single file.

Compiling using a specific Handlebars version

You can use different versions of Handlebars by specifying the version in your package.json and passing it as options.handlebars:

package.json

{
  "devDependencies": {
    "handlebars": "^1.3.0"
  }
}

gulpfile.js

gulp.task('templates', function(){
  gulp.src('source/templates/*.hbs')
    .pipe(handlebars({
      handlebars: require('handlebars')
    }))
    .pipe(wrap('Handlebars.template(<%= contents %>)'))
    .pipe(declare({
      namespace: 'MyApp.templates',
      noRedeclare: true, // Avoid duplicate declarations
    }))
    .pipe(concat('templates.js'))
    .pipe(gulp.dest('build/js/'));
});

The runtime you include on the client side MUST match the version you compile templates with. You cannot use the the 2.x runtime with 1.x templates. The handlebars1 example copies the runtime from node_modules/handlebars/dist/handlebars.runtime.js and uses that on the client side. Follow a similar pattern in your application to keep the runtime up to date with the compiler.

Compiling to separate modules for Node/Browserify

This example will make templates available for loading via Node's require:

gulpfile.js

var handlebars = require('gulp-handlebars');
var defineModule = require('gulp-define-module');

gulp.task('templates', function(){
  gulp.src(['templates/*.hbs'])
    .pipe(handlebars())
    .pipe(defineModule('node'))
    .pipe(gulp.dest('build/templates/'));
});

Templates can then be used within Node as such:

var appTemplate = require('./build/templates/App.Header.js');
var html = appTemplate(data);

Compiling to a single module for use in Node/Browserify

See the singleModule example if you'd like to have a single module that contains all of your templates that can be used like so:

yourApp.js

var templates = require('./templates');
var output = templates.App.header();

Processing the generated template AST

The example below removes any partial and replaces it with the text foo.

gulpfile.js

handlebars({
  processAST: function(ast) {
    ast.statements.forEach(function(statement, i) {
      if (statement.type === 'partial') {
        ast.statements[i] = { type: 'content', string: 'foo' };
      }
    });
  }
})

Using HTMLBars with Ember

See the ember-htmlbars example for details

handlebars({
  handlebars: emberHandlebars,
  compiler: emberTemplateCompilerFunction
})

API

handlebars(options)

options.compilerOptions

Type: Object

Compiler options to pass to Handlebars.precompile().

options.processAST

Type: Function

A function which will be passed the parsed Handlebars Abstract Syntax Tree. You can modify the AST in place or return a new AST to change the source of the precompiled template.

options.handlebars

Type: Object

Handlebars library to use for precompilation. By default, the latest stable version of Handlebars is used.

options.compiler

Type: Function

Custom compiler function. By default, the precompile method of the provided Handlebars module is used (see options.handlebars).