gistfile1.js

new Ajax.request(YOUR_URL_HERE, {
  method: 'get',
  onSuccess: function(response) {
    new S2.UI.Autocompleter('autocompleter2', {
    choices: response.responseJSON.map(function(o) { return o.client }),
    choiceAttribute: 'name',
    listTemplate: new Template('#{text} <em>(#{object.login})</em>')
  },
  onFailure: function(response) {
    // Handle failure here
  }
});