javascript中判断语句 js 判断函数

一、从浏览器url中获取到所需参数及信息；

function getQueryString(name) {
 var that = this;
 if(isNULL(name)){return null}  //调用isnull
 var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)", "i");
 var r = window.location.search.substr(1).match(reg);
 var param;
  try{
  param = decodeURI(r[2]);
  }catch(e){
  return null;
  }
 if (isNULL(r) == false) {
 return param;
  }
 return null;
}getQueryString("name");调用函数输入入参即可获取url中的name值；

二、判断为空

function isNULL(exp){
return !!(exp == null || typeof exp == "undefined" || exp == 0 || exp == "null" || exp == [] || exp == '{}' ||                 exp == '' || exp == {});},

三、判断空对象

function isEmptyObject( obj ) {
  var name;
 for ( name in obj ) {
  return false;
  }
   return true;
}