1、搜索框，默认值为“请输入账户",当获取焦点时清空文本内容，失去焦点时，若文本内容为空或空格，则将文档本人重置为”请输入账户"。
<script type="text/javascript">
function Focus(){
var a = document.getElementById("account1");
if(a.value == "请输入账户"){
a.value = "";
}
}
function Blur(){
var a = document.getElementById("account1");
if(a.value.trim()==""){
a.value="请输入账户";
}
}
</script>
</head>
<body>
<input id="account1" type="text" value="请输入账户" name="account" onfocus="Focus();" onblur="Blur()";/>
</body>
2、添加标签。
<div id="creatediv1" style="50px;height: 50px;background-color: red;></div>
<input type="button" value="添加" onclick="creatediv2();" />
<script type="text/javascript">
function creatediv1(){
var cobj = document.createElement("a");
cobj.href = "http://www.baidu.com";
cobj.innerText = "百度";
var nid = document.getElementById("creatediv1");
nid.appendChild(cobj)
}
function creatediv2(){
var nid = document.getElementById("creatediv1");
var tag = "<a href='http://www.baidu.com'>百度</a>";
//beforeBein在div之前，beforeEnd在div内部，afterBegin在div内部，afterEnd在div后面
nid.insertAdjacentHTML("beforeBegin",tag);
}
</script>
3、设置获取标签属性
var n = document.getElementById("creatediv1");
n.setAttribute("sb","ooxx");
console.log(n);
b = n.getAttribute("sb");
console.log(b);
特殊：n.className，n,style.fontSize="100px"。
效果：
4、提交表单。
<form id="form1" action="https://www.sogou.com/web" >
<input name="query" type="text">
</form>
<button onclick="Submit();">提交</button>
<script type="text/javascript">
function Submit(){
document.getElementById("form1").submit();
}
</script>
5、修改表单默认行为。
<form id="form1" action="https://www.sogou.com/web" >
<input id="input1" name="query" type="text">
</form>
<button onclick="return Submit();">提交</button>
<script type="text/javascript">
function Submit(){
var a = document.getElementById("input1");
if(a.value.trim()){
return true;
}else {
alert("请输入内容");
return false;
}
}
</script>
6、定时器。
<head>
<meta charset="UTF-8">
<title>欢迎电神莅临指导</title>
</head>
<body>
<button onclick="stop();">停止</button>
<script type="text/javascript">
function stop(){
clearInterval(obj);
}
var obj = setInterval("run()",1000);
function run(){
var a = document.title;
var f = a.charAt(0);
var sub = a.substring(1, a.length);
var new_t = sub + f;
document.title = new_t;
}
</script>
</body>
7、