​x
 
<!DOCTYPE html>
<html>
<body>
​
<p>只要 i 小于 5，点击按钮就可以循环遍历一段代码。</p>
​
<button onclick="myFunction()">试一试</button>
​
<p id="demo"></p>
​
<script>
function myFunction() {
  var text = "";
  var i = 0;
  do {
    text += "<br>The number is " + i;
    i++;
  }
  while (i < 5);
  document.getElementById("demo").innerHTML = text;
}
</script>
​
</body>
</html>
​