The TemplateCache
provides a cache for retrieving templates
from script blocks in your HTML. This will improve
the speed of subsequent calls to get a template.
To use the TemplateCache
, call the get
method on TemplateCache directly.
Internally, instances of the TemplateCache type will be created and stored
but you do not have to manually create these instances yourself. get
will
return a compiled template function.
var template = Backbone.Marionette.TemplateCache.get("#my-template");
// use the template
template({param1:'value1', paramN:'valueN'});
Making multiple calls to get the same template will retrieve the template from the cache on subsequence calls.
You can clear one or more, or all items from the cache using the
clear
method. Clearing a template from the cache will force it
to re-load from the DOM (via the loadTemplate
function which can be overridden, see below) the next time it is retrieved.
If you do not specify any parameters, all items will be cleared from the cache:
Backbone.Marionette.TemplateCache.get("#my-template");
Backbone.Marionette.TemplateCache.get("#this-template");
Backbone.Marionette.TemplateCache.get("#that-template");
// clear all templates from the cache
Backbone.Marionette.TemplateCache.clear()
If you specify one or more parameters, these parameters are assumed
to be the templateId
used for loading / caching:
Backbone.Marionette.TemplateCache.get("#my-template");
Backbone.Marionette.TemplateCache.get("#this-template");
Backbone.Marionette.TemplateCache.get("#that-template");
// clear 2 of 3 templates from the cache
Backbone.Marionette.TemplateCache.clear("#my-template", "#this-template")
If you want to use an alternate template engine while
still taking advantage of the template caching functionality, or want to customize
how templates are stored and retrieved, you will need to customize the
TemplateCache object
. The default operation of TemplateCache
, is to
retrieve templates from the DOM based on the containing element's id
attribute, and compile the html in that element with the underscore.js
template
function.
The default template retrieval is to select the template contents
from the DOM using jQuery. If you wish to change the way this
works, you can override the loadTemplate
method on the
TemplateCache
object.
Backbone.Marionette.TemplateCache.prototype.loadTemplate = function(templateId){
// load your template here, returning the data needed for the compileTemplate
// function. For example, you have a function that creates templates based on the
// value of templateId
var myTemplate = myTemplateFunc(templateId);
// send the template back
return myTemplate;
}
The default template compilation passes the results from
loadTemplate
to the compileTemplate
function, which returns
an underscore.js compiled template function. When overriding compileTemplate
remember that it must return a function which takes an object of parameters and values
and returns a formatted HTML string.
Backbone.Marionette.TemplateCache.prototype.compileTemplate = function(rawTemplate) {
// use Handlebars.js to compile the template
return Handlebars.compile(rawTemplate);
}