<script> function myFunction() { var x="",i=0; while (i<5) { x=x + "The number is " + i + "------"; i++; document.getElementById("demo"+i).innerHTML=x; } document.getElementById("xdemo1").innerHTML=x; document.getElementById("xdemo2").innerHTML=x; document.getElementById("xdemo3").innerHTML=x; document.getElementById("xdemo4").innerHTML=x; } </script> </body> </html>
注意这行:x=x + "The number is " + i + "<br>"; 每一次循环都是在前一行的基础上增加一行第一次循环后x是 The number is 0 第二次循环后x是 The number is 0 The number is 1 第三次循环后x是 The number is 0 The number is 1 The number is 2 第四次循环后x是 The number is 0 The number is 1 The number is 2 The number is 3 第五次循环后x是 The number is 0 The number is 1 The number is 2 The number is 3 The number is 4你最后看到的是第五次循环后的结果
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<p>点击下面的按钮,只要i小于5 就一直循环代码块.</p>
<button onclick="myFunction()">点击这里</button>
<p id="demo1"></p>
<p id="demo2"></p>
<p id="demo3"></p>
<p id="demo4"></p>
<p id="demo5"></p>
<hr>
<p id="xdemo1"></p>
<p id="xdemo2"></p>
<p id="xdemo3"></p>
<p id="xdemo4"></p>
<p id="xdemo5"></p>
<script>
function myFunction()
{
var x="",i=0;
while (i<5)
{
x=x + "The number is " + i + "------";
i++;
document.getElementById("demo"+i).innerHTML=x;
}
document.getElementById("xdemo1").innerHTML=x;
document.getElementById("xdemo2").innerHTML=x;
document.getElementById("xdemo3").innerHTML=x;
document.getElementById("xdemo4").innerHTML=x;
}
</script>
</body>
</html>
每一次循环都是在前一行的基础上增加一行第一次循环后x是
The number is 0
第二次循环后x是
The number is 0
The number is 1
第三次循环后x是
The number is 0
The number is 1
The number is 2
第四次循环后x是
The number is 0
The number is 1
The number is 2
The number is 3
第五次循环后x是
The number is 0
The number is 1
The number is 2
The number is 3
The number is 4你最后看到的是第五次循环后的结果