function left_zero_4(str) {
   if (str != null && str != '' && str != 'undefined') {
    if (str.length == 2) {
     return '00' + str;
    }
   }
   return str;
  }

function unicode(str){
   var value='';
   for (var i = 0; i < str.length; i++) {
    value += '\\u' + left_zero_4(parseInt(str.charCodeAt(i)).toString(16));
   }
   return value;
  }
  function left_zero_4(str) {
   if (str != null && str != '' && str != 'undefined') {
    if (str.length == 2) {
     return '00' + str;
    }
   }
   return str;
  }

function reconvert(str){ 
   str = str.replace(/(\\u)(\w{1,4})/gi,function($0){ 
    return (String.fromCharCode(parseInt((escape($0).replace(/(%5Cu)(\w{1,4})/g,"$2")),16))); 
   }); 
   str = str.replace(/(&#x)(\w{1,4});/gi,function($0){ 
    return String.fromCharCode(parseInt(escape($0).replace(/(%26%23x)(\w{1,4})(%3B)/g,"$2"),16)); 
   }); 
   str = str.replace(/(&#)(\d{1,6});/gi,function($0){ 
    return String.fromCharCode(parseInt(escape($0).replace(/(%26%23)(\d{1,6})(%3B)/g,"$2"))); 
   }); 
   
   return str; 
  }

  function unicode1(str){ 
   var value='';
   for (var i = 0; i < str.length; i++)
    value += '&#' + str.charCodeAt(i) + ';';
   return value;
  } 

  function ascii(str){ 
   var value='';
   for (var i = 0; i < str.length; i++) {
    value += '\&#x' + left_zero_4(parseInt(str.charCodeAt(i)).toString(16))+';';
   }
   return value;
  } 

  <script type="text/javascript">
  function a(pChoice){
   var inputEle = document.getElementById('input_area');
   var outputEle = document.getElementById('output_area');
   switch(pChoice){ 
    case "CONVERT_FMT1":
     outputEle.value = ascii(inputEle.value);
     break; 
    case "CONVERT_FMT2":
     outputEle.value = unicode(inputEle.value);
     break; 
    case "CONVERT_FMT3":
     outputEle.value = unicode1(inputEle.value);
     break; 
    case "RECONVERT":
     outputEle.value = reconvert(inputEle.value);
     break; 
   } 
  } 
  function ascii(str){ 
   var value='';
   for (var i = 0; i < str.length; i++) {
    value += '\&#x' + left_zero_4(parseInt(str.charCodeAt(i)).toString(16))+';';
   }
   return value;
  } 
  function unicode(str){
   var value='';
   for (var i = 0; i < str.length; i++) {
    value += '\\u' + left_zero_4(parseInt(str.charCodeAt(i)).toString(16));
   }
   return value;
  }
  function left_zero_4(str) {
   if (str != null && str != '' && str != 'undefined') {
    if (str.length == 2) {
     return '00' + str;
    }
   }
   return str;
  }
  function unicode1(str){ 
   var value='';
   for (var i = 0; i < str.length; i++)
    value += '&#' + str.charCodeAt(i) + ';';
   return value;
  } 
  function reconvert(str){ 
   str = str.replace(/(\\u)(\w{1,4})/gi,function($0){ 
    return (String.fromCharCode(parseInt((escape($0).replace(/(%5Cu)(\w{1,4})/g,"$2")),16))); 
   }); 
   str = str.replace(/(&#x)(\w{1,4});/gi,function($0){ 
    return String.fromCharCode(parseInt(escape($0).replace(/(%26%23x)(\w{1,4})(%3B)/g,"$2"),16)); 
   }); 
   str = str.replace(/(&#)(\d{1,6});/gi,function($0){ 
    return String.fromCharCode(parseInt(escape($0).replace(/(%26%23)(\d{1,6})(%3B)/g,"$2"))); 
   }); 
   
   return str; 
  }
  </script>

<style>
textarea {
 width: 100%;
 height: 200px;
 resize:vertical;
 border: 1px solid #CCC;
 /*border-radius:8px;*/
 padding:4px;
 box-shadow: 2px 2px 5px #d3d6da;
 -moz-box-shadow: 2px 2px 5px #d3d6da;
}
</style>
提供一个中文汉字Unicode互转、 ASCII与Unicode互转的在线工具，方便帮助你解决中文的乱码问题。

   <div class='divider'></div>
   <textarea id="input_area" name="input_area" placeholder="贴入要处理的Unicode或Ascii字符" value="">jb51.net - 编程素材网</textarea>
   <div class='row'>
    <button onclick="javascript:a('CONVERT_FMT2');">中文汉字转Unicode</button>
    <button onclick="javascript:a('RECONVERT');">Unicode转中文汉字</button>  
    <button onclick="javascript:a('RECONVERT')">ASCII转换Unicode</button>
    <button onclick="javascript:a('CONVERT_FMT3');">Unicode转换ASCII</button>
    <button onclick="javascript:a('CONVERT_FMT1');">中文转换&#XXXX</button>
   </div>
<textarea name="output_area" id="output_area" onclick="this.select();" placeholder="处理之后的Unicode或Ascii字符" value=""></textarea>