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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>JS打印一个三角形</title>
</head>
<body>
<script type="text/javascript">
var i="0";
var x="*";
while(i<30){
var h=1;
while(h<=i){
document.write(x)
h++
}
document.write('<br>')
i++
document.write('<center>')
}
</script>
</body>
</html>点击 "运行实例" 按钮查看在线实例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>jS乘法口诀</title>
</head>
<body>
<script type="text/javascript">
for (var i = 1; i <= 9; i++) {
for (var j =i; j<= 9; j++) {
var kong=" "
if (i*j<10) {
kong+=" "
}
document.write(i+'x'+j+'='+(i*j)+kong)
}
document.write('<br>')
}
</script>
</body>
</html>点击 "运行实例" 按钮查看在线实例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>jS乘法口诀</title>
</head>
<body>
<script type="text/javascript">
for (var i = 1; i <= 9; i++) {
for (var j =1; j<=i; j++) {
var kong=" "
if (i*j<10) {
kong+=" "
}
document.write(i+'x'+j+'='+(i*j)+kong)
}
document.write('<br>')
}
</script>
</body>
</html>点击 "运行实例" 按钮查看在线实例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>打印三角形</title>
</head>
<body>
<script type="text/javascript">
var i=1;
var x="*";
while(i<=30){
var j=1; //j=1是初始化变量这里是每循环一次输出*号再换个行每次循环星号的个数加一
while(j<=i){
document.write(x);
j++ //就是只要while(j<=i)条件成立那么就会执行并输出document.write(x)+1
}
document.write("<br>");
i++ //外层的循环市为了输出换行,里面的循环市为了输出星号
}
</script>
<!-- 关于双while循环的理解：当i<=30的时候执行第二个循环j，当j小于等于i的时候执行输出“*”那这里的*为什么会每一次会增加1呢？为什么不是不直接x++? -->
</body>
</html>点击 "运行实例" 按钮查看在线实例
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