<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<div id="div1"></div>
<div class="div2"></div>
</body>
</html>
<script>
var div1=document.getElementById("div1"); //id選擇器
div1.innerHTML="我能<br/>干什么";
// div1.innerText="我能<br/>干什么"; 不認<br/>
// div1.innerText+="新增的內容";
var div2=document.getElementsByClassName("div2")[0]; //class選擇器
div2.innerHTML="隨便";
div2.style.width="100px";
div2.style.height="100px";
div2.style.background="red";
div2.setAttribute("hidden","hidden");
div2.removeAttribute("hidden");
// var div3=document.getElementsByName();
// var div4=document.getElementsByTagName(); //標簽選擇器。