title: How to get the value of one of the key-value pairs of JSON in JavaScript？
body: <p>I want to get the value of gid in JavaScript</p>
  
  <pre><code>alert(JSON.stringify(data); √
  alert(JSON.stringify(data['responseJSON']['gid'])); ×
  </code></pre>
  
  <p>I tried to use it like this but I got an error.</p>
  
  <p>I found a lot of answers but still can't get the value I need.</p>
  
  <pre class="lang-js prettyprint-override"><code>{
    "form": {},
    "files": [{}],
    "filenames": ["timg.jpg"],
    "filescount": 1,
    "extra": {},
    "response": {
      "success": true,
      "msg": "image url after upload",
      "gid": 81
    },
    "reader": {},
    "jqXHR": {
      "readyState": 4,
      "responseText": "{\"success\":true,\"msg\":\"image url after upload\",\"gid\":81}",
      "responseJSON": {
        "success": true,
        "msg": "image url after upload",
        "gid": 81
      },
      "status": 200,
      "statusText": "OK"
    }
  }
  
  
  alert(JSON.stringify(data));
  </code></pre>
  
  
  
  <p>I want to get the value of gid (81)，but it is not use.</p>