title: Node.js convert Chinese character to \uXXXX
body: <p>I want to convert the string like '字符串' to '\u5B57\u7B26\u4E32', how do I implement in Node.js?</p>
  
  <pre><code>function convert(str) {
      //...
  }
  
  var s = '字符串'
  convert(s); // =&gt; \u5B57\u7B26\u4E32
  </code></pre>