title: Object fields sequence
body: <p>I have a JavaScript object written in javascript code as below:</p>
  
  <pre><code>var rtnStr = {"000":"area000","020":"area020","030":"area030",
                "040":"area040","047":"area047","049":"area049",
                "050":"area050","060":"area060","070":"area070",
                "100":"area100", "900":"area900"};
  
  for (var key in rtnStr) {
    document.write('rtnStr[' + key + ']= ' + rtnStr[key] + '&lt;br /&gt;');
  }
  </code></pre>
  
  <p>then I run the code in browser, I got the result:</p>
  
  <pre><code>rtnStr[100]= area100
  rtnStr[900]= area900
  rtnStr[000]= area000
  rtnStr[020]= area020
  rtnStr[030]= area030
  rtnStr[040]= area040
  rtnStr[047]= area047
  rtnStr[049]= area049
  rtnStr[050]= area050
  rtnStr[060]= area060
  rtnStr[070]= area070
  </code></pre>
  
  <p>the object fields(keys) sequence is not the same as I have declare, How can I got the result as below?</p>
  
  <pre><code>rtnStr[000]= area000
  rtnStr[020]= area020
  rtnStr[030]= area030
  rtnStr[040]= area040
  rtnStr[047]= area047
  rtnStr[049]= area049
  rtnStr[050]= area050
  rtnStr[060]= area060
  rtnStr[070]= area070
  rtnStr[100]= area100
  rtnStr[900]= area900
  </code></pre>