document.getElementById("clock") is null

i have a clock time inside my form..it run as a current time same with PC time.. i'm use this code:

    <script language="javascript">
            var int=self.setInterval("clock()",1000);
            function clock()
                             {
                                var d=new Date();
                                document.getElementById("clock").value=d.getHours() + ":"+d.getMinutes()+ ":" +d.getSeconds();
                           }
      </script>

<input type="text" id="clock" name="time">

but after click submit the clock automatically pause...and show error at firebugs 开发者_如何学Pythondocument.getElementById("clock") is null... how to make it works normally by using jquery code?

Difficult to tell exactly what you are trying to ask here, but this is the "jQuery" version of what you're doing:

function updateClock() {
  var d=new Date();
  $("#clock").val(d.getHours() + ":"+d.getMinutes()+ ":" +d.getSeconds());
}
setInterval(updateClock,1000);

Put the code inside document ready function in jquery.

$(function(){
    var interval=self.setInterval("clock()",1000); 

    function clock() 
    { 
        var d=new Date(); 
        $("#clock").val(d.getHours() + ":"+d.getMinutes()+ ":" +d.getSeconds()); 
    } 
});