xxxxxxxxxx<html><head><meta charset="utf-8"><title>W3Cschool教程(w3cschool.cn)</title></head><body><p>单击按钮每3秒出现一个“Hello”警告框。</p><p>再次点击警告框，经过3秒出现新的警告框，这将一直执行 ...</p><button onclick="myFunction()">点我</button><script>function myFunction(){ setInterval(function(){alert("Hello")},3000);}</script></body></html>