2.0.9 • Public • Published


    Handlebars templates via Async/await for Koa

    Build Status


    koahub-handlebars is middleware. We stash an instance of koahub-handlebars for you in the library so you don't have to manage it separately. Configure the default instance by passing an options hash to #middleware. To render a template then, just await ctx.render('templateName');. Here's a basic app demonstrating all that:

    var koa = require('koa');
    var hbs = require('koahub-handlebars');
    var app = koa();
    // koahub-handlebars is middleware. `use` it before you want to render a view
        extname: '.html',
        viewPath: './www',
        layoutsPath: './www',
        partialsPath: './www'
    // Render is attached to the koa context. Call `ctx.render` in your middleware
    // to attach rendered html to the koa response body.
    app.use(async function (ctx, next) {
      //set theme
      ctx.state.theme = 'home';
      await ctx.render('main', {title: 'koahub-handlebars'});

    After a template has been rendered, the template function is cached. #render accepts two arguements - the template to render, and an object containing local variables to be inserted into the template. The result is assigned to Koa's this.response.body.


    The plan for koahub-handlebars is to offer identical functionality as express-hbs (eventaully). These options are supported now.

    viewPath required

    Type: Array|String
    Full path from which to load templates


    Pass your own instance of handlebars


    Type: Object
    Hash of handlebars options to pass to template()


    Alter the default template extension (default: '.hbs')


    Full path to partials directory


    Name of the default layout


    Full path to layouts directory


    Alter contentFor helper name


    Alter block helper name


    Disable template caching

    Registering Helpers

    Helpers are registered using the #registerHelper method. Here is an example using the default instance (helper stolen from official Handlebars docs:

    hbs = require('koahub-handlebars');
    hbs.registerHelper('link', function(text, url) {
      text = hbs.Utils.escapeExpression(text);
      url  = hbs.Utils.escapeExpression(url);
      var result = '<a href="' + url + '">' + text + '</a>';
      return new hbs.SafeString(result);

    Your helper is then accessible in all views by using, {{link "Google" "http://google.com"}}

    The registerHelper, Utils, and SafeString methods all proxy to an internal Handlebars instance. If passing an alternative instance of Handlebars to the middleware configurator, make sure to do so before registering helpers via the koahub-handlebars proxy of the above functions, or just register your helpers directly via your Handlebars instance.

    You can also access the current Koa context in your helper. If you want to have a helper that outputs the current URL, you could write a helper like the following and call it in any template as {{requestURL}}.

    hbs.registerHelper('requestURL', function() {
      var url = hbs.templateOptions.data.koa.request.url;
      return url;

    Registering Partials

    The simple way to register partials is to stick them all in a directory, and pass the partialsPath option when generating the middleware. Say your views are in ./views, and your partials are in ./views/partials. Configuring the middleware via

      viewPath: __dirname + '/views',
      partialsPath: __dirname + '/views/partials'

    will cause them to be automatically registered. Alternatively, you may register partials one at a time by calling hbs.registerPartial which proxies to the cached handlebars #registerPartial method.


    Passing defaultLayout with the a layout name will cause all templates to be inserted into the {{{body}}} expression of the layout. This might look like the following.

    <!DOCTYPE html>

    In addition to, or alternatively, you may specify a layout to render a template into. Simply specify {{!< layoutName }} somewhere in your template. koahub-handlebars will load your layout from layoutsPath if defined, or from viewPath otherwise. If viewPath is set to an Array of paths, the first path in the array will be assumed to contain the layout named.

    At this time, only a single content block ({{{body}}}) is supported.

    Overriding Layouts using Locals

    As of version 0.9.0, it's possible to override the layout used for rendering, using locals. For example:

    router.get('/', async function (ctx, next) {
      await this.render('foo', {
        layout: 'bar'

    See the tests for more.

    Block content

    Reserve areas in a layout by using the block helper like so.

    {{#block "sidebar"}}
      <!-- default content for the sidebar block -->

    Then in a template, use the contentFor helper to render content into the block.

    {{#contentFor "sidebar"}}

    Disable Template Caching

    To disable the caching of templates and partials, use the disableCache option. Set this option to false to open caching. Default is true. Remember to set this option to false for production environments, or performance could be impacted!


    Application local variables ([this.state](https://github.com/koajs/koa/blob/master/docs/api/context.md#ctxstate)) are provided to all templates rendered within the application.

    app.use(async function (ctx, next) {
      this.state.title = 'My App';
      this.state.email = 'me@myapp.com';
      await next();

    The state object is a JavaScript Object. The properties added to it will be exposed as local variables within your views.

    <p>Contact : {{email}}</p>


    You can run the included example via npm install koa and node --harmony app.js from the example folder.

    Unsupported Features

    Here's a few things koahub-handlebars does not plan to support unless someone can provide really compelling justification.

    Async Helpers

    koahub-handlebars does not support asynchronous helpers. No, really - just load your data before rendering a view. This helps on performance and separation of concerns in your app.

    Handlebars Version

    As of koahub-handlebars@0.9.0, the version of the Handlebars dependency bundled with this module has been updated to 4.0.x. If this causes conflicts for your project, you may pass your own instance of Handlebars to the module, or downgrade to the last 0.8.x version.


    Functionality and code were inspired/taken from koahub-handlebars. Many thanks to @jwilm for authoring this middleware.


    npm i koahub-handlebars

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