custom-helpers.js

var HB = require('yui/handlebars').Handlebars;
var Y  = require('yui/base');

var helpers = {
    foo: function () {
        return 2;
    }
};

var t = HB.compile('{{foo}}/{{bar}}/{{#baz}}{{xyz}}{{/baz}}');

console.log(t({
    bar: 1,
    baz: {
        xyz: 3
    }
}, {
    partials: {},
    helpers: Y.merge(helpers, HB.helpers)
}));