js练习 表单非空验证 省级联动 输出最大值

js 用户填写非空验证

<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<form action="index.html" method="get" onsubmit="return checkLogin()">
			
			<p>用户名<input type="text" id="tv_uname"/><span id="tv_uname_span"></span></p>
			<p>密码<input type="password" id="tv_upsw"/><span id="tv_upsw_span"></span></p>
			<p><input type="submit" value="提交"/></p>
		</form>
		<script type="text/javascript">
			
			function checkLogin(){
				document.getElementById("tv_uname_span").innerHTML="";
				document.getElementById("tv_upsw_span").innerHTML="";
				
				var name = document.getElementById("tv_uname").value;
				if(name==null||name==""){
					document.getElementById("tv_uname_span").innerHTML="用户名不能空";
					return false;
				}
				var psw = document.getElementById("tv_upsw").value;
				if(psw==null||psw==""){
					document.getElementById("tv_upsw_span").innerHTML="密码不能空";
					return false;
				}
				return true;
			}
		</script>
	</body>
</html>

js练习 表单非空验证 省级联动 输出最大值

js 省级联动

<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<select onchange="show(this.value)">
			<!--this.value就是index,也就是当前的value-->
			<option value="0">北京市</option>
			<option value="1">长沙市</option>
			<option value="2">郴州市</option>
		</select>
		<select id="tv_select">
			
		</select>
		<script type="text/javascript">
			
			var num = [["一区","二区","三区"],["4区","5区","6区"],["7区","8区","9区"]];
			var select = document.getElementById("tv_select");
//			select等于节点
			function show(index){
				var citys = num[index];
//				citys等于三个区
				var temp = "";
				for(var i=0;i<citys.length;i++){
					temp+="<option>"+citys[i]+"</option>";
//					三个区都在
				}
				select.innerHTML=temp;
//				三个区赋值给节点
			}
		</script>
		
	</body>
</html>

js练习 表单非空验证 省级联动 输出最大值

js 输出最大值

<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<form>
			<p>数值1 <input type="text" class="s"</p>	
			<p>数值2 <input type="text" class="s"</p>
			<p>数值3 <input type="text" class="s"</p>
			<p>最大值 <input type="text" id="max"</p>
			<p><input type="button" value="计算最大值" onclick="show()"</p>	
		</form>
		
		<script type="text/javascript">
			var sum = document.getElementsByClassName("s");
			var temp = sum[0].value;
			function show(){
				for(var i=0;i<sum.length;i++){
					if(temp<sum[i].value){
						temp=sum[i].value;
					}
				}
				document.getElementById("max").value=temp;
			}
		</script>
	</body>
</html>

js练习 表单非空验证 省级联动 输出最大值

js练习 表单非空验证 省级联动 输出最大值

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