Handlebars block helper for only outputting when a property is defined

handlebars-defined-helper.js

// only output the block if the object property exists/is defined
//
// {{#defined property}}
//   Property exists
// {{/defined}}

Handlebars.registerHelper('defined', function(property, block) {
  return typeof(this[property]) !== 'undefined' ? block(this) : '';
});