title: javascript get key name from array of objects
body: <p>from </p>
  
  <pre><code>"data":[{"ja":"大阪市"},{"en":"Osaka"}]
  </code></pre>
  
  <p>I want to get <code>"ja"</code> and <code>"en"</code>.</p>
  
  <p>I tried several ways...</p>
  
  <pre><code>data.map(function(_, i) { return i; });
  </code></pre>
  
  <p>it returns 
  array of numbers.</p>
  
  <pre><code>console.log(Object.keys(Object.values(data)));
  </code></pre>
  
  <p>all trials return</p>
  
  <pre><code>(2) [0, 1]
  0: 0
  1: 1
  </code></pre>
  
  <p>what can I do ??
  please answer me. thank you.</p>