title: Setting the value binding of a textarea to an element of an observableArray
body: <p>I've got a bunch of text boxes that are supposed to hold the value for a number of separate elements in an observableArray. The number of text boxes depends on how many "properties" a user selects on an earlier screen, and the properties can be added and removed at will later on. Currently, I'm starting with an empty array and attempting to set the value binding of the textbox as a new key in the array:</p>
  
  <pre><code>&lt;input type="text" class="tdEdit" data-bind="value: listing.properties[property_id]"/&gt;
  </code></pre>
  
  <p>Listing is an object that has <code>var properties = ko.observableArray([])</code> defined in it. My goal is to have properties array look something like <code>{"property1": "3", "property2": "4"}</code>, etc. Currently, though, the properties array always remains empty.</p>
  
  <p>Hopefully that makes some sort of sense.</p>