title: Get key with minimum value
body: <p>I have an array like this: <code>arr = {lst1: 300, lst2: 381, lst3: 4, lst4: 4, lst5: 49, …}</code></p>
  
  <p>And I'm trying get the lowest value with key using Javascript.</p>
  
  <p>What I've tried:</p>
  
  <p><code>alert(Math.min.apply(Math, arr));</code> returns <code>Infinity</code> I don't know why</p>
  
  <p>I got this on Google, just for try:</p>
  
  <pre><code>var keys = Object.keys(arr).map(Number).filter(function(a){
      return arr[a];
  }); alert(Math.min.apply(Math, keys));
  </code></pre>
  
  <p>returns <code>Infinity</code> too </p>
  
  <p>I want something more complete, like this output: "The lowest value is 2 from lst9".</p>
  
  <p>I really tried fix it myself before asking here, but without success!
  Can you help me fix this "Infinity" issue? Thank you.</p>