<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>js练习</title>
</head>
<body>
<h2>1.使用递归算法计算n的阶乘：n!</h2>
<script type="text/javascript">
function jieCheng(n){
if(n==1){
return 1;
}else{
return n*jieCheng(n-1);
}
}
document.write("5!="+jieCheng(5)+'</br>');
</script>
<h2>2.输出1000-9999直接的所有回文。</h2>
<script type="text/javascript">
function huiWen(m){
qianWei=Math.floor(m/1000);
baiWei=Math.floor(m%1000/100);
shiWei=Math.floor(m%100/10);
geWei=m%10;
if(qianWei==geWei&&baiWei==shiWei){
return m;
}else{
return null;
}
}
j=0;
for(i=1000;i<=9999;i++){
result=huiWen(i);
if(result!=null){
document.write(result+',');
j++;
if(j%10==0){
document.write('</br>');
}
}
}
</script>
<h2>3.利用循环函数输出字符*，构成一个圣诞树的形状。</h2>
<script type="text/javascript">
function shengDanShu(z){
for(x=1;x<=z;x++){
for(y=1;y<=z-x;y++){
document.write(' ');
}
for(k=1;k<=2*x-1;k++){
document.write('*');
}
document.write('</br>');
}
}
shengDanShu(6);
</script>
</body>
</html>