I'm learning Backbone.js and am trying to figure out whether it's possible to have instance variables in Backbone views.
My goal is to load a view's templates from an external file when a view is being instantiated. Currently I'm storing them in a global variable in the Backbone app's global namespace, but it would be cleaner to store the templates in a view's instance variables. Currently I have it set up like this:
var templates = {};
MessageView = Backbone.View.extend({
initialize: function() {
$.get('js/Test2Templates.tpl', function(doc) {
var tmpls = $(doc).filter('template');
templates['MessageView'] = [];
tmpls.each(function() {
templates.MessageView[this.id] = $.jqotec($.unescapeHTML(this.innerHTML));
});
});
},
render: function() {
var tpldata = {name: 'Ville', thing: 'Finland'};
$('#display').jqoteapp(templates.MessageView.greeting_template, tpldata);
},
events: {
"click input[type=button]": "additionalTransactions"
},
additionalTransactions: function() {
this.render();
}
});
But instead of using "templates" being defined as a global var, I'd like to create 'templates' in a view's initialize function, along these lines (but this doesn't work):
MessageView = Backbone.View.extend({
view_templates: {},
initialize: function() {
$.get('js/Test2Templates.tpl', function(doc) {
var tmpls = $(doc).filter('template');
tmpls.each(function() {
this.view_templates[this.id] = $.jqotec($.unescapeHTML(this.innerHTML));
});
});
},
render: function() {
var tpldata = {name: 'Ville', thing: 'Suomi'};
$('#display').jqoteapp(this.view_templates.greeting_template, tpldata);
},
events: {
"click input[type=button]": "additionalTransactions"
},
additionalTransactions: function() {
this.render();
}
});
This is probably (?) pretty straightforward and/or obvious, but me being somewhere on the Backbone.js learning curve, I'd much appreciate any help with this!! Thanks!
Backbone. Backbone has been around for a long time, but it's still under steady and regular development. It's a good choice if you want a flexible JavaScript framework with a simple model for representing data and getting it into views.
The Backbone. js View el method defines the element that is used as the view reference. this. el is created from the view's tagName, className, id and attributes properties, if specified.
Backbone. js is a minimalistic framework which aims to provide a simple set of data structures and features that you can use to create a structured web application's front-end.
Backbone. js is a model view controller (MVC) Web application framework that provides structure to JavaScript-heavy applications. This is done by supplying models with custom events and key-value binding, views using declarative event handling and collections with a rich application programming interface (API).
Your view_templates
instance variable is fine (and a good idea as well). You just have to be sure that you're using the right this
inside your $.get()
callback and inside your tmpls.each()
call. I think you want your initialize
to look more like this:
initialize: function() {
this.view_templates = { };
var _this = this;
$.get('js/Test2Templates.tpl', function(doc) {
var tmpls = $(doc).filter('template');
tmpls.each(function() {
_this.view_templates[this.id] = $.jqotec($.unescapeHTML(this.innerHTML));
});
});
},
I'm not sure which this.id
you want inside the tmpls.each()
but I'm guessing that you want the DOM id
attribute from the current template so I left it as this.id
.
The this.view_templates
assignment in your constructor (initialize
) is needed because you presumably want each instance of the view to have its own copy of the array. Creating a new view instance doesn't do a deep copy of the the view so if you just have:
MessageView = Backbone.View.extend({
view_templates: {},
// ...
then all the instances will end up sharing the same view_templates
object and view_templates
will behave more like a class variable than an instance variable.
You can specify your instance variables in the view definition (i.e. the Backbone.View.extend()
call) as a form of documentation but you will want to initialize any of them that should behave as an instance variable in your initialize
method; read-only or "class variables" like events
can be left as part of the view's definition.
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