//设置url中参数值

function setParam(param,value){

    var query = location.search.substring(1);

    var p = new RegExp("(^|)" + param + "=([^&]*)(|$)");

    if(p.test(query)){

        //query = query.replace(p,"$1="+value);

        var firstParam=query.split(param)[0];

        var secondParam=query.split(param)[1];

        if(secondParam.indexOf("&")>-1){

            var lastPraam=secondParam.split("&")[1];

            return  '?'+firstParam+'&'+param+'='+value+'&'+lastPraam;

        }else{

            if(firstParam){

                return '?'+firstParam+'&'+param+'='+value;

            }else{

                return '?'+param+'='+value;

            }

        }

    }else{

        if(query == ''){

            return '?'+param+'='+value;

        }else{

            return '?'+query+'&'+param+'='+value;

        }

    }

}

//调用

var url=window.location.href;//获取当前url

var searchUrl=setParam("beginDate",date);

if(url.indexOf("?")>0){

    =url.split("?")[0];

}

window.location.href=url+searchUrl;