循环变量<html lang="en">
<head>
<meta charset="UTF-8">
<title>循环变量</title>
</head>
<body>
<script>
/*1+2+3+...10*/
var i = 1; //循环变量的定义
var sum = 0;
while (i <= 10) { //循环变量的判断
if (i % 2 == 0) {
sum = sum + i; //循环变量的更新
}
i++;
}
alert(sum);
</script>
</body>
</html>
结果图：
求出100到1000的水仙花数
<html lang="en">
<head>
<meta charset="UTF-8">
<title>求出100到1000的水仙花数</title>
</head>
<body>
<script>
var i = 100;
while (i <= 999) {
var i1 = i % 10;
var i2 = parseInt(i / 10 % 10);
var i3 = parseInt(i / 100);
if (i == Math.pow(i1, 3) + Math.pow(i2, 3) + Math.pow(i3, 3)) {
alert(i);
}
i++;
}
</script>
</body>
</html>
结果图：
累加求和
<html lang="en">
<head>
<meta charset="UTF-8">
<title>累加求和</title>
</head>
<body>
<script>
var sum = 0;
var num = parseInt(prompt("输入您要累加的数"));
while (num != -1){
sum += num;
num = parseInt(prompt("请输入您要累加的数"));
}
alert(sum);
</script>
</body>
</html>
结果图：
例：输入5和3得到8
do-while语句<html lang="en">
<head>
<meta charset="UTF-8">
<title>do-while</title>
</head>
<body>
<script>
var i = 1; //循环变量的初始化
var sum = 0;
do {
sum += i;
i++; //循环变量的更新
} while (i <= 10); //循环变量的判断
alert(sum);
</script>
</body>
</html>
结果图：
循环的嵌套
<html lang="en">
<head>
<meta charset="UTF-8">
<title>循环的嵌套</title>
</head>
<body>
<script>
var i = 1;
var sum1 = 0;
while (i <= 5) {
var j = 1;
while (j <= i) {
sum1 += j;
j++;
}
i++;
}
alert(sum1);
</script>
</body>
</html>
结果图：
阶乘
<meta charset="UTF-8">
<title>阶乘</title>
</head>
<body>
<script>
var i = 1;
var sum = 0;
while(i <= 5 ){
var j = 1;
var sum1 = 1;
while(j <= i ){
sum1 = sum1*j;
j++;
}
sum += sum1;
i++;
}
alert(sum);
</script>
</body>
</html>
结果图：
for循环
<html lang="en">
<head>
<meta charset="UTF-8">
<title>for循环</title>
</head>
<body>
<script>
var sum = 0;
for(var i = 1;i <= 100; i ++){
sum +=i;
}
alert(sum);
</script>
</body>
</html>
结果图：
break语句
<html lang="en">
<head>
<meta charset="UTF-8">
<title>break语句</title>
</head>
<body>
<script>
var sum = 0;
for (var i = 1;i <= 100;i ++){
sum += i;
if (sum >= 2000){
alert(i+":"+sum);
break;
}
}
</script>
</body>
</html>
结果图：
嵌套循环的break语句
<html lang="en">
<head>
<meta charset="UTF-8">
<title>嵌套循环的break语句</title>
</head>
<body>
<!--1+(1+2)+(1+2+3)+(1+2+3+4)+(1+2+3+4+5)-->
<script>
var sum = 0;
var i = 1;
while (i <= 5){
var j = 1;
while(j <= i ){
if (i == 3){
break;
}
sum += j;
j++;
}
i++;
}
alert(sum);
</script>
</body>
</html>
结果图：
九九乘法表
<html lang="en">
<head>
<meta charset="UTF-8">
<title>九九乘法表</title>
</head>
<body>
<script>
for(var i=1;i<=9;i++){/*外层循环控制显示的行数*/
for(var j=1;j<=i;j++){
var sum =i*j;
document.write(i+"*"+j+"="+sum+" ");
}document.write("<br>");
}
</script>
</body>
</html>
结果图：
continue语句</title> </head>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>continue语句</title>
</head>
<body>
<script>
var sum = 0;
for (var i = 1; i <= 100; i++) {
if (i % 3 == 0) {
continue;
}
sum += i;
}
alert(sum);
</script>
</body>
</html>
结果图：
时间： 2025-01-03 08:19:00