自动检查并替换文本框内的字符

  <HTML>

  <HEAD>

  <META http-equiv='Content-Type' content='text/html; charset=gb2312'>

  <TITLE>自动检查并替换文本框内的字符</TITLE>

  <SCRIPT LANGUAGE="JavaScript">

  <!-- Begin

  function replaceChars(entry) {

  out = "a"; // 要替代的字母

  add = "z"; // 替换后的字母

  temp = "" + entry;

  while (temp.indexOf(out)>-1) {

  pos= temp.indexOf(out);

  temp = "" + (temp.substring(0, pos) + add +

  temp.substring((pos + out.length), temp.length));

  }

  document.subform.text.value = temp;

  }

  // End -->

  </script>

  </HEAD>

  <BODY >

  <center>

  <form name="subform">

  <input type=text name=text size=40 value="abcdabcd"><br>

  <input type=button name=action value="Done!" onClick="replaceChars(document.subform.text.value);">

  </form>

  </center>

  

  </BODY></HTML>