How do I add a separator between elements in an {{#each}} loop except after the last element?

I have a Handlebars template where I'm trying to generate a comma-separated list of items from an array.

In my Handlebars template:

{{#each list}}
    {{name}} {{status}},
{{/each}}

I want the , to not show up on the last item. Is there a way to do this in Handlebars or do I need to fall back to CSS selectors?

UPDATE: Based on Christopher's suggestion, this is what I ended up implementing:

var attachments = Ember.CollectionView.extend({
    content: [],
    itemViewClass: Ember.View.extend({
        templateName: 'attachments',
        tagName: 'span',
        isLastItem: function() {
            return this.getPath('parentView.content.lastObject') == this.get('content');
        }.property('parentView.content.lastObject').cacheable()
    })
}));

and in my view:

{{collection attachments}}

and the item view:

{{content.title}} ({{content.size}}) {{#unless isLastItem}}, {{/unless}}

I know I'm late to the parts but I found a WAYYYY simpler method

{{#unless @last}},{{/unless}}

Since Ember v1.11 you are able to get the index of an each using block parameters. In your case this would look something like this:

{{#each list as |item index|}}
    {{if index ", "}}{{item.name}} {{item.status}}
{{/each}}

The first index value will be 0 which will evaluate to false and will not be added, all subsequent values will evaluate to true which will prepend a separator.

You can use standard CSS to do this:

li:after {
    content: ',';
}

li:last-of-type:after {
    content: '';
}

I prefer separate rules, but a more concise if slightly less readable version (from @Jay in the comments):

li:not(:last-of-type):after {
    content: ',';
}

I have created sep block helper:

Handlebars.registerHelper("sep", function(options){
	if(options.data.last) {
		return options.inverse();
	} else {
		return options.fn();
	}
});

Usage:

{{#each Data}}
   {{Text}}{{#sep}},{{/sep}}
{{/each}}

Supports else statement.

I realize this is a year old but I had a similar problem and wound up here. In my case, I was actually dealing with an array. So, here's my solution.

Handlebars.registerHelper('csv', function(items, options) {
    return options.fn(items.join(', '));
});

// then your template would be
{{#csv list}}{{this}}{{/csv}}

I was going for a simple and elegant solution that keeps the csv logic in the template.

With ember 2.7 you can do this after you install ember-truth-helpers:

ember install ember-truth-helpers

and then your template will look like this:

{{#each model as |e|}}
    {{e}}{{#unless (eq e model.lastObject)}}, {{/unless}}
{{/each}}

I got this working with a modified version of freak3dot's answer:

handlebars.registerHelper('csv', function(items, options) {
  return items.map(function(item) {
    return options.fn(item)
  }).join(', ')
})

(This is a node app, so change the map accordingly to underscore or whatever if you're building in the browser)

Allows for formatting objects between each comma:

{{#csv players}
  {{firstName}} {{lastName}}
{{/csv}}

Edit: Here's a more flexible version. Join a list of things on an arbitrary separator.

handlebars.registerHelper('join', function(items, separator, options) {
  return items.map(function(item) {
    return options.fn(item)
  }).join(separator)
})

And template:

{{#join players ' vs '}
  {{firstName}} {{lastName}}
{{/join}}

Maybe for this context, you should be creating a view for the collection, not an iteration of views on the member items. In this case, a Handlebar iterator is overkill. In my example below, changes to the firstName or lastName on the Person objects will be bound to the list and update the view.

Template:

{{App.listController.csv}}

Javascript:

App = Ember.Application.create();

var Person = Ember.Object.extend({
	firstName: null,
	lastName: null
});

var bob = Person.create({
	firstName: "bob",
	lastName: "smith"
});

var ann = Person.create({
	firstName: "ann",
	lastName: "doe"
});

App.listController = Ember.Object.create({
	list: [bob, ann],
	csv: Ember.computed(function () {
		var arr = [];
		this.get('list').forEach(function (item, index, self) {
			arr.push(item.firstName + ' ' + item.lastName);
		})
		return arr.join(',');
		}).property('[email protected]', '[email protected]')
});
// any changes to bob or ann will update the view
bob.set('firstName', 'tim');
// adding or removing from the array will update the view
App.listController.get('list').pushObject(Person.create(firstName: "Jack", lastName:"Dunn"});

Below is my original answer, that didn't work for this context.

You should be able to do this with a helper:

Handlebars.registerHelper('csv', function(items, options) {
  var out = "";
  for(var i=0, l=items.length; i<l; i++) {
	out += options.fn(items[i]);
	if (i < l - 1) {
		out += ',';
	}
	// might want to add a newline char or something
  } 
  return out;
});

// then your template would be
{{#csv list}} {{name}} {{status}} {{/each}}