Determining the last loop index in ractive template

Question

Basically I want to this: In Mustache templating is there an elegant way of expressing a comma separated list without the trailing comma? in a Ractive template.

For the object

{
  "items": [
    {"name": "red"},
    {"name": "green"},
    {"name": "blue"}
  ]
}

I want to produce "red, green, blue"
I want to know if I am at the last item, so I can know whether to print the separator. Something like:

{{#items:i}}{{name}} {{#i.is_last}},{{/i}}{{/items}}  

Answer 1

Can't easily test this right now, but wouldn't something like the following work?

{{#items:i}}
    {{name}} {{ i < (items.length-1) ? "," : "" }}
{{/items}}

Answer 2

Can confirm that Stephen Thomas' answer works. Another option would be to join the array items like so:

ractive = new Ractive({
  el: 'body',
  template: '{{ items.map( getName ).join( ", " ) }}',
  data: {
    items: [{ name: 'red' }, { name: 'green' }, { name: 'blue' }],
    getName: function ( item ) {
      return item.name;
    }
  }
});

Answer 3

I actually wanted a solution that would allow me to put something more complicated instead of a comma, say, a DOM element. I figured out (another) method that works.

{{#items:i}}
  {{name}}{{#(i<(items.length-1))}}, {{/end}}
{{/items}}

Answer 4

Recently @index and @last magic variables are introduced, so the example now becomes more readable:

{{#items}}
  {{.name}}{{#@index !== @last}}, {{/}}
{{/}}