javascript 关于倒计时与输入框选中状态的判断

<script type="text/javascript">
function dianji(){
    setTimeout("alert('执行成功');",7000);
    }

</script>
<button onclick="dianji()">点击</button>
<script type="text/javascript">
var scr=0;
var time=setInterval("times()",1000);
function times(){
    document.getElementById("wang").innerHTML=scr++;
    }
function tingzhi(){
    clearInterval(time);
    }    
</script>


<p id="wang">0</p>
<button onclick="tingzhi()">停止</button>
<script type="text/javascript">
function shiqu(objec){
    if(objec.value.length<4){
        alert("长度不够");
        objec.focus();
        objec.select();
        }
    }
</script>
<input type="password" onblur="shiqu(this)" />