Rails-like options_for_select helper for Handlebars

options_for_select.js

// Create a set of HTML option tags for each of the supplied inputs. If the inputs are arrays
// themselves, it is assume they are of the form [displayName, value].
// 
// e.g.
//   directions = ['North', 'South']
//   {{options_for_select directions}}
//
// results in:
//   <option>North</option>
//   <option>South</option>
// 
// e.g.
//   directions = [['North', 'n'], ['South', 's']]
//   {{options_for_select directions}}
//
// results in:
//   <option value="n">North</option>
//   <option value="s">South</option>
//
// To set the default selected value in the list, pass a second value with
// the desired value.
//
// e.g.
//   directions = [['North', 'n'], ['South', 's']]
//   selected   = 'n'
//   {{options_for_select directions selected}}
//
// results in:
//   <option value="n" selected="selected">North</option>
//   <option value="s">South</option>
//
Handlebars.registerHelper('options_for_select', function(items, selected) {
  var output = '', display, value;
  for (var i = 0; i < items.length; i++) {
    if (items[i] instanceof Array) {
      display = items[i][0];
      value   = items[i][1];
    } else {
      display = value = items[i];
    }
    
    if (value == selected) {
      output = output + '<option value="' + value + '" selected="selected">' + display + '</option>';
    } else {
      output = output + '<option value="' + value + '">' + display + '</option>';
    }
  }
  return new Handlebars.SafeString(output);
});