JS复制内容（兼容IE和Firefox）

// <![CDATA[
function copy_clip(copy) {
 if (window.clipboardData) {
  window.clipboardData.setData("Text", copy);
 } else if (window.netscape) {
  try {
   netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
  } catch (e) {
   alert("被浏览器拒绝！\n请在浏览器地址栏输入[about:config]并回车\n然后将[signed.applets.codebase_principal_support]属性设置为[true]");
  }
  var clip = Components.classes['@mozilla.org/widget/clipboard;1'].createInstance(Components.interfaces.nsIClipboard);
  if (!clip) {
   return;
  }
  var trans = Components.classes['@mozilla.org/widget/transferable;1'].createInstance(Components.interfaces.nsITransferable);
  if (!trans) {
   return;
  }
  trans.addDataFlavor('text/unicode');
  var str = new Object();
  var len = new Object();
  var str = Components.classes["@mozilla.org/supports-string;1"].createInstance(Components.interfaces.nsISupportsString);
  var copytext = copy;
  str.data = copytext;
  trans.setTransferData("text/unicode",str,copytext.length*2);
  var clipid = Components.interfaces.nsIClipboard;
  if (!clip) {
   return false;
  }
  clip.setData(trans,null,clipid.kGlobalClipboard);
 }
 alert("已复制代码到剪贴板")
 return false;
}
// ]]>
<input type="button" value="复制" class="input_copy" onclick="copy_clip(document.getElementByIdx_x('test').value)">