Summary of HTML tags that are confusing and error-prone-PHP Tutorial-php.cn

Summary of HTML tags that are confusing and error-prone

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Release： 2016-08-08 09:19:54

Original

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After struggling for a day, I finally have a clear understanding of the correct use of HTML tags and their respective applicability. Here is a brief summary to avoid making similar mistakes again.

Everything is due to such a problem

<html>
<head>
</head>
<body>
	<form id="form1" method="get" >	
		用户名：<input type="text" id="name" name="name" />
		<p id="username"></p>
		<br />
		密码：<input type="password" id="password" name="password" />
		
		<button type="submit" /button>		
	</form>

	<script>
	window.x=document.getElementById("username");
	window.
	{
		document.getElementById('name').focus();
	}
	//
	function mUp()
	{	
		if(document.getElementById('name').value=="")
		{
			x.innerHTML = "用户名不能为空";
			//alert("不能为空");
		}
		else
			document.getElementById('form1').action="/login";
	}
	</script>	
</body>
</html>

Copy after login

Run the above code and click the "Login" button when nothing is entered. It will prompt "The user name cannot be empty", but it will crash after only appearing once. What is the reason?

The key is that there will be two events triggered by

<button type="submit" /button>

Copy after login

at this time. First, call the function corresponding to onclick, and then automatically submit (because the type is submit at this time), which will naturally overwrite the prompt. So setting the type to button can solve the problem.

The following is a brief summary,

HTML tag's type attribute

value	description
button	defines clickable buttons (In most cases, used through JavaScript startup script ).
checkbox	Define checkboxes.
file	Define input fields and "Browse" button for file upload.
hidden	Define hidden input fields.
image	Define the submit button in the form of an image.
password	Define the password field. Characters in this field are masked.
radio	Define radio buttons.
reset	Define the reset button. The reset button clears all data in the form.
submit	Define the submit button. The submit button will send the form data to the server.
text	Define a single-line input field where the user can enter text. The default width is 20 characters.