0412作业

var banJing = parseInt(prompt("请输入圆的半径"));
    var x = m(banJing);
    alert(x);
    function m(banJing){
        if(banJing > 0){
            var mianJi = banJing * banJing * Math.PI;
        }
        return mianJi;
    }

s();
    function s (){
        var mydate=new Date();
        var y = mydate.getFullYear();
        var m = mydate.getMonth();
        var d = mydate.getDate();
        var x = mydate.getHours()
        var f = mydate.getMinutes()
        var mm = mydate.getSeconds()
        document.write(y+"-"+(m+1)+"-"+d+"&nbsp"+"&nbsp"+x+":"+f+":"+mm);
    }