javascript - uncaught TypeError: Cannot call method 'replace' of undefined backbone.js

Question

I 'm trying to develop a simple RSS app using backbone.js. I 'm using this backbone.js tutorial. I 'm getting the following error, on line 2(template), when defining the template. Can someone also tell me why is tagName: "li" defined in the tutorial?

uncaught TypeError: Cannot call method 'replace' of undefined backbone.js

Javscript

window.SourceListView = Backbone.View.extend({
    tagName:"li",
    template: _.template($('#tmpl_sourcelist').html()),

    initialize:function () {
        this.model.bind("change", this.render, this);
        this.model.bind("destroy", this.close, this);
    },

    render:function (eventName) {
        $(this.$el).html(this.template(this.model.toJSON()));
        return this;
    },

    close:function () {
        $(this.el).unbind();
        $(this.el).remove();
    }
});

HTML

 <script type="text/template" id="tmpl_sourcelist">
                        <div id="source">
                        <a href='#Source/<%=id%>'<%=name%></a>
                        </div>
                </script>

thanks

Answer 1

You're getting your error right here:

template: _.template($('#tmpl_sourcelist').html()),

Part of _.template's internals involves calling String#replace on the uncompiled template text on the way to producing the compiled template function. That particular error usually means that you're effectively saying this:

_.template(undefined)

That can happen if there is no #tmpl_sourcelist in the DOM when you say $('#tmpl_sourcelist').html().

There are a few simple solutions:

1. Adjust your <script> order so that your #tmpl_sourcelist comes before you try to load your view.

2. Create the compiled template function in your view's initialize instead of in the view's "class" definition:

   window.SourceListView = Backbone.View.extend({
       tagName:"li",
       initialize:function () {
           this.template = _.template($('#tmpl_sourcelist').html());
           //...
   

As far as tagName goes, the fine manual has this to say:

el view.el

[...] this.el is created from the view's tagName, className, id and attributes properties, if specified. If not, el is an empty div.

So having this in your view:

tagName: 'li'

means that Backbone will automatically create a new <li> element as your view's el.