js 截取URL中的某個參數的值

function getQuerystring(key)

{

  //key = key.replace(/[\[]/," \\\[").replace(/[\]]/,"\\\]");

  var regex = new RegExp("[\\?&]"+key+"=([^&#]*)&?",["i"]);

  var qs = regex.exec(window.location.href);

  if(qs == null)

    return '';

  else

    return qs[1];

}