title: Is there something similar to sessionStorage but with multidimensional keys?
body: <p>I'd like to save off values of a tree-like structure locally, then retrieve them based on user interaction.  After some research, I found that <code>sessionStorage</code> (or <code>localStorage</code>) might be a good way to go about doing this.  But I'm having trouble saving nested data.</p>
  
  <p>Normally you have:</p>
  
  <pre><code>sessionStorage['key'] = 'someString';
  </code></pre>
  
  <p>I tried to implement something like:</p>
  
  <pre><code>sessionStorage['key1'] = [];
  sessionStorage['key1']['key2'] = 'someString';
  </code></pre>
  
  <p>but I got an <code>undefined</code> error.</p>
  
  <p>I've checked out few other storage libraries, but they only offer that single key-value pair option. Is there anything I'm missing?</p>