Partials template in underscore (just like in handlebars)?

Question

I have a backbone model like this

var PeopleModel = Backbone.Model.extend({
defaults: {              
    \"people\": [
          { \"username\": \"alan\", \         


        

Answer 1

Or to avoid using global scope you can mix in global template helpers like so:

(function() {
    var originalUnderscoreTemplateFunction = _.template;
    var templateHelpers = {};

    _.mixin({
        addTemplateHelpers : function( newHelpers ) {
            _.extend( templateHelpers, newHelpers );
        },

        template : function(text, data, settings) {
            // replace the built in _.template function with one that supports the addTemplateHelpers
            // function above. Basically the combo of the addTemplateHelpers function and this new
            // template function allows us to mix in global "helpers" to the data objects passed
            // to all our templates when they render. This replacement template function just wraps
            // the original _.template function, so it sould be pretty break-resistent moving forward.

            if( data )
            {
                // if data is supplied, the original _.template function just returns the raw value of the
                // render function (the final rentered html/text). So in this case we just extend
                // the data param with our templateHelpers and return raw value as well.

                _.defaults( data, templateHelpers ); // extend data with our helper functions
                return originalUnderscoreTemplateFunction.apply( this, arguments ); // pass the buck to the original _.template function
            }

            var template = originalUnderscoreTemplateFunction.apply( this, arguments );

            var wrappedTemplate = function( data ) {
                _.defaults( data, templateHelpers );
                return template.apply( this, arguments );
            };

            return wrappedTemplate;
        }
    }
}

Then call

_.addTemplateHelpers( {
    partial : function() {
        return _.template(
            $('#' + which + '-partial').html(),
            data
        );
    }
} );

Here is a link to the underscore mixin on github.

Answer 2

No, there is no native partial support in Underscore's templates. But, you can put pretty much any JavaScript you want inside <% ... %>; in particular, you can call your own functions so you can add something partial-ish without much difficulty. You could have a template like this:

<script id="people-template" type="text/x-handlebars-template">
    <% _(people).each(function(person) { %>
      <%= partial('person', person) %>
    <% }) %>
</script>

and then add a partial function to window:

window.partial = function(which, data) {
    var tmpl = $('#' + which + '-partial').html();
    return _.template(tmpl)(data);
};

Demo: http://jsfiddle.net/ambiguous/HDuj5/9/

That's not quite as slick and pretty as {{> ... }} in Handlebars but Underscore's templates are a very thin wrapper around JavaScript itself and that limits you somewhat. You can use namespaces to avoid putting things directly in window or you could use the {variable: ...} option to _.template and a wrapper to set up your standard helpers.

Answer 3

I think this is similar to Dave's answer, but perhaps requiring less code:

function partialTemplate(origTemplate, partialValues){
    return function(values){
        return origTemplate(_.defaults(values, partialValues));
    };
}

Example usage:

var t = _.template('<%= val1 %>,<%= val2 %>'); // original template requiring 2 values
var pt = partialTemplate(t, {val1:1}); // partial template with 1 value pre-populated
pt({val2:2}); // returns '1,2'
pt({val2:3}); // returns '1,3'