JavaScript-表单验证

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>表单验证</title>
	<style>
		input,button{
			box-sizing: border-box;
			300px;
			padding:10px;
			font-size:16px;
			line-height: 18px;
			border:1px solid #ccc;
		}
		button{
			background:#f5f5f5;
		}
	</style>
</head>
<body>
	<form action="1.php" name="myForm" onsubmit="return checkForm()">
		<table>
			<tr>
				<td>用户名</td>
				<td>
					<input type="text" name="usernameInput" autofocus tabindex="0">
				</td>
			</tr>
			<tr>
				<td>邮箱</td>
				<td>
					<input type="text" name="emailInput">
				</td>
			</tr>
			<tr>
				<td>密码</td>
				<td>
					<input type="password" name="pwdInput">
				</td>
			</tr>

			<tr>
				<td>确认密码</td>
				<td>
					<input type="password" name="repwdInput">
				</td>
			</tr>

			<tr>
				<td></td>
				<td>
					<button>注册</button>
				</td>
			</tr>
		</table>
	</form>
	<script>
	/**
	 * 表单很特殊
	 * 可以不通过document.getElementById获取元素
	 * 直接通过name属性获取元素
	 */
		function checkForm(){
			//验证 用户名 
			var usernameValue = document.myForm.usernameInput.value;
			if (usernameValue.search(/^w{6,12}$/) === -1) {
				alert("用户名必须是6~12位的数字、字母、下划线");
				return false;
			}
			//验证邮箱
			var emailValue = document.myForm.emailInput.value;
			if (emailValue.match(/^[w-]+@[w-]+(.w+){1,3}$/) === null) {
				alert("请输入正确的邮箱")
				return false;
			}

			//验证密码
			var pwdValue = document.myForm.pwdInput.value;
			if (pwdValue.length < 6 || pwdValue.length > 18) {
				alert("密码必须是6~18位");
				return false;
			}
			//确认密码
			var repwdValue = document.myForm.repwdInput.value;
			if (repwdValue !== pwdValue) {
				alert("两次密码不一致");
				return false;
			}
			return true;
		} 
		/**
		  * 邮箱格式:
          *  test@qq.com
             user@sina.com.cn
             user-name@abc.com
             user_name@qq.com
		*/
	</script>
</body>
</html>
原文地址:https://www.cnblogs.com/1666818961-lxj/p/7450492.html