gistfile1.txt

function Challenge(name){
    var self = this;

    self.name;
}

function GBKAuthedViewModel() {
    var self = this;

    // other stuff...
    self.challenges = ko.observableArray([new Challenge('challenge1'),new Challenge('challenge2')]);

// then in the view
      <ul class="challenge-list" data-bind="foreach: challenges">
        <li data-bind="text: name"></li>
      </ul>