template.js

    /**
     * Map object keys in string to its values
     * 
     * @param {String} text
     * @param {Object} data
     * @return {String}
     */
    template: function (text, data) {
        return !text ? '' : text.replace(/\{([^\}]+)\}/g, function (value, key) {
            return key in data ? data[key] : value;
        });
    },

Usage:

var htmlSpan = '<span class="{className}">{content}</span>';
var button = utils.template(htmlSpan, {
      className: this.className('button'),
      content:   text
});