Javascript 禁用backspace鍵返回上頁作法

先提供參考網址 http://people-k.blogspot.tw/2008/05/javascript-backspace.html http://followmeyo.blogspot.tw/2013/12/javascript-backspace.html 附上我修改過的 IE、FireFox、Chrome都可以用
<script language="JavaScript">
  if (window.navigator.userAgent.indexOf("MSIE") >= 1) {
    document.onkeydown = check;
  } else if (window.navigator.userAgent.indexOf("Firefox") >= 1) {
    document.onkeypress = check;
  } else {
    document.onkeydown = check;
  }
  function check(e) {
    var code;
    if (!e) var e = window.event;
    if (e.keyCode) code = e.keyCode;
    else if (e.which) code = e.which;
    if (code == 8) {
      code = 0;
      return false;
    }
    return true;
  }
</script>