<script type="text/javascript">
document.writeln('------------------<br />')
document.writeln ('Output triangle: <br />')
for (var i = 1; i <= 5; i ++)
{
// document.writeln ('*')
// judge the current line
/// i means the current line number
// i === 1 means the first line
//
// i === 5 means the fifth line
for (j = 1; j <= i; j ++)
{
// i === 1 j === 1 1
// i === 2 j === 2 1 2
// i === 3 j === 3 1 2 3
document.writeln ('*')
}
document.writeln (' <br /> ')
}
document.writeln (' ------------------ <br /> ')
document.writeln (' Output inverted triangle: <br /> ')
for (var i = 1; i <= 5; i ++)
{
// document.writeln (' * ')
// five in the first line
// four in the second line
//
// one in the fifth line
for (var j = i; j <= 5;j++)
{
// i===1 j===1 2 3 4 5
// i===2 j===2 3 4 5
// i===3 i===3 4 5
document.writeln('*')
}
document.writeln('<br />')
}
document.writeln('------------------<br />')
document.writeln('输出等腰三角：<br />')
for (var i=1;i<=5;i++)
{
// 准备空格
var str=''
for (var j=i;j<=5;j++)
{
str+=' '
}
document.writeln(str)
// document.writeln('<br />')
// 准备*号
for (var k=1;k<=i;k++)
{
document.writeln('*')
}
document.writeln('<br>')
}
document.writeln('------------------<br />') for (var i = 1; i <= 5; i ++)
document.writeln ('Output inverted isosceles triangle: <br />')
{
//准备空格
var str=''
for (var j=1;j<=i;j++)
{
str+=' '
}
document.writeln(str)
//准备*号
for (var k=i;k<=5;k++)
{
document.writeln('*')
}
document.writeln('<br />')
}
document.writeln('------------------<br />')
document.writeln('输出正三角(数字)：<br />')
for (var i=1;i<=5;i++)
{
for (var j=1;j<=i;j++)
{
document.writeln(j)
}
document.writeln('<br />')
}
document.writeln('------------------<br />')
document.writeln('输出倒三角(数字)：<br />')
for (var i=1;i<=5;i++)
{
for (var j=i;j<=5;j++)
{
document.writeln(j)
}
document.writeln('<br />')
}
</script>