<!DOCTYPE html>charset="utf-8"W3Cschool教程(w3cschool.cn)点击按钮创建及增加字符串变量。onclick="myFunction()"点击这里id="demo"function myFunction(){var x=5+5;var y="5"+5;var z="Hello"+5;var demoP=document.getElementById("demo");demoP.innerHTML=x + "<br>" + y + "<br>" + z;}