问题
I'm finding the restrictions of handlebar templates in Ember.js to be absolutely crippling. You can't execute arbitrary javascript. All you get is a fixed set of abilities (if/else, each, action, view, outlet) and the ability to output the value of a property on the current context object.
Which means I cannot figure out how to do something as simple as utilizing a loop counter in order to, for example, slap positional IDs on an html element inside a loop based on it's position in the collection I'm iterating on.
It doesn't make sense to add it as a computed property on the model, because that's not model-level knowledge (the same model could be in two different positions in different views).
FYI-Using Ember-1.0-pre, Ember-Data, and Rails with ActiveModel::Serializers on PostgreSQL.
回答1:
I'd recommend writing a handlebars helper, in which you can execute arbitrary javascript. See http://handlebarsjs.com for some examples.
Alternatively, you could include the positional IDs on your child views (not your models).
回答2:
With handlebars.js (v. 1.0.rc1) I could do this:
{{#each links}}
<li>{{@index}} - {{url}}</li>
{{/each}}
回答3:
Turns out providing a loop counter is the exact subject of the final example on this page:
http://handlebarsjs.com/block_helpers.html
(Dan G already pointed out the "writing a helper" solution in his answer, but since there's already a published example, I wanted to create a fresh answer to make the link more prominent.)
来源：https://stackoverflow.com/questions/12331780/generating-a-loop-counter-in-ember-js-each