Building Applications with Backbone and Laravel: JST

13thApril 2014 | Tags:

You might well be used to developing Backbone views like this:

MyApp.Views.SomeView = Backbone.View.extend({    
  template: _.template('<ul><% _.each(items, function(item){ %><li><%= item %></li><% }); %></ul>'),    
  el: '#some-element',

This is all fine and well for simple structures, but can quickly get unwieldly if you're building markup of any significant size or complexity. It can also lead to all sorts of issues around readability.

One alternative is to put more complex templates into separate HTML files:

// file: folder/template.html

<ul>
 <% _.each(items, function(item){ %>
 <li> <%= item %> </li>
 <% }); %>
</ul>

Each time you want to render a template, you can load in the template via AJAX or use RequireJS's text plugin. Great for development, but pretty atrocious for performance, as it'll fire off untold numbers of HTTP requests.

Using JST allows you to develop templates in this way - spreading templates across separate files, organised into a logical hierarchy -- but "collapse" them into variables which are available via a single JS file. This file can then be minified, or incorporated into a larger Javascript file using, for example, the RequireJS optimiser or Google Closure Compiler.

Such a file looks a little like this:

// file: jst.js

var JST = JST || {};
JST['app/templates/folder/template.html'] = _.template('<ul><% _.each(items, function(item){ %><li><%= item %></li><% }); %></ul>');
JST['app/templates/folder/template2.html'] = _.template('...');
JST['app/templates/folder2/template.html'] = _.template('...');
// etc...

JST and Laravel

If your Backbone application's back-end uses Laravel, I've written a package to generate such a file.

Usage

Generate your JST file by entering the following command in your terminal:

php artisan jst:generate

Or alternatively, you can have it "watch" your templates directory (and any sub-directories) for changes, and recompile the file for you:

php artisan jst:watch

Back to your Backbone application:

// file: namespace.js

define([
    // Libs
    "jquery",
    "use!underscore",
    "use!backbone"
],

function($, _, Backbone) {
 // Put application wide code here

 return {
  // This is useful when developing if you don't want to use a
  // build process every time you change a template.
  //
  // Delete if you are using a different template loading method.
  fetchTemplate: function(path, done) {
   var JST = window.JST = window.JST || {};
   var def = new $.Deferred();

   // Should be an instant synchronous way of getting the template, if it
   // exists in the JST object.
   if (JST[path]) {        
    if (_.isFunction(done)) {
     done(JST[path]);
    }

    return def.resolve(JST[path]);
   }

   // Fetch it asynchronously if not available from JST, ensure that
   // template requests are never cached and prevent global ajax event
   // handlers from firing.
   $.ajax({
    url: path,
    type: "get",
    dataType: "text",
    cache: false,
    global: false,

    success: function(contents) {
     JST[path] = _.template(contents);

     // Set the global JST cache and return the template
     if (_.isFunction(done)) {
      done(JST[path]);
     }

     // Resolve the template deferred
     def.resolve(JST[path]);
    }
   });

   // Ensure a normalized return value (Promise)
   return def.promise();
  },

 };
});

As you can see, this provides a method which tries to load a template from a global variable called JST, but if that's not available -- i.e., during development -- then it loads it in as an HTML file using AJAX.

Now you can create a view like this, to take advantage of it:

MyApp.Views.SomeView = Backbone.View.extend({
 template: "app/templates/folder/someview.html",        
    render: function(done) {      
  namespace.fetchTemplate(this.template, function(tmpl) {        
   view.el.innerHTML = tmpl({model: view.model.toJSON() });
   if (_.isFunction(done)) {
    done(view.el);
   }  
  });
 }
// …

Using it Outside of Laravel

There's no reason why this code can't be re-purposed to work outside of Laravel -- perhaps I'll get a chance at some point, but feel free to have a stab at it. All the dependencies are managed via Composer.

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