一个简单的计时器，在小于10的时候补零怎么实现？

Question

<script>
        var js =0;
        var a= 0;
        var b=0;
        var d=0;
        
    function my(){
        document.getElementById("values").value = js;
        
        function jl(i){
            if(i<10){
                i="0"+i;
                }
            return i;
            }
        js = js+1;
        if(js==60){
            js=0;
            a+=1;
            }
        document.getElementById("demo").innerHTML = a;
        b = setTimeout(my,1000);
    }

    function go(){
        if(!d){
            d=1;
            my();
            }
        }
    function stop(){
        clearTimeout(b);
        d=0;
    }

</script>

Answer 1

	<script type="text/javascript">
		var js = 0;
		var a = 0;
		var b = 0;
		var d = 0;

		function jl(i) {
			if (i < 10) {
				i = "0" + i;
			}
			return i;
		}

		function my() {
			document.getElementById("values").value = js;
			js = js + 1;
			if (js == 60) {
				js = 0;
				a += 1;
			}
			document.getElementById("demo").innerHTML = jl(a) + ":" + jl(js);
			b = setTimeout(my, 1000);
		}

		function go() {
			if (!d) {
				d = 1;
				my();
			}
		}

		function stop() {
			clearTimeout(b);
			d = 0;
		}
	</script>
	<input type="text" id="values" value="0"/>
	<div id="demo">00:00</div>
	<input type="button" value="go" onclick="go();" />
	<input type="button" value="stop" onclick="stop();" />