javascript settimeout timeout

javascript setTimeOut 

var oldVariable_code="";
function clock()
{
     // javascript time clock date
     now = new Date();hours = now.getHours();minutes = now.getMinutes();seconds = now.getSeconds();
     $.ajax({url: "heartbeat"})
     timeValue = hours+':'+((minutes < 10) ? "0":"") + minutes + ":"+((seconds < 10) ? "0":"") + seconds ;
     //_refreshv("clock",timeValue);
     newVariable_code=_lookup("Variable_code");
     if (oldVariable_code!=newVariable_code){
        setCookie("VariableCODE",newVariable_code,1);
        company(newVariable_code,"NAME","company");
        setCookie("VariableCOMPANY",_lookup('company'),1);
        History()
        oldVariable_code=newVariable_code;
     }
     setTimeout("clock()",1000);
}
clock();