title: JsRender: how to get value from map with specified key
body: <p>well I render my data into my page like this:</p>
  
  <pre><code>$('#component_data').html($('#component_data_tpl').render(result, extra_opts));
  </code></pre>
  
  <p>here 'result' is a big map returned from my ajax request, which contains all data, e.g., </p>
  
  <pre><code>result: { data1: { 'a': 1, 'b':2}, data2: {...}, ... }
  </code></pre>
  
  <p>so how to render data1['a'], when I know for sure the key is 'a' in my template code without a loop to iterate all values in data1? Do I have to create a helper function?</p>
  
  <hr>
  
  <p><strong>edit:</strong></p>
  
  <p>sorry, maybe it's not a good example above.
  i'm iterating data1:</p>
  
  <pre><code>{{props data1}}
      {{&gt;key}}
  {{/props}}
  </code></pre>
  
  <p>however, I want to get data from data2, whose keys are the same as those in data1. Is there a way like:</p>
  
  <pre><code>{{props data1}}
      {{&gt;key}}
      {{&gt; data2[key]}}
  {{/props}}
  </code></pre>
  
  <p>to do this?
  All I know now is to use a helper function, then pass (key, #data.parent) to resolve associated data value, but writing a helper function every time is a bit tedious.</p>