<script type="text/javascript">

function dianji(){

    setTimeout("alert('执行成功');",7000);

    }

</script>

<button οnclick="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 οnclick="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" οnblur="shiqu(this)" />