SOURCE

function GetQueryString(name) {
  var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)");
  var r = window.location.search.substr(1).match(reg);
  if (r != null) return decodeURIComponent(r[2]);
  return null;
}

// 调用方式
var second_channel = GetQueryString("second_channel")