Ensuring the User Provides a Value
Description
The simplest kind of input validation is to ensure that the user provides a value. You do this with the required attribute.
The user cannot submit the form until a value has been provided.
Example
The following code shows the required attribute in use.
<!DOCTYPE HTML>
<html>
<body>
<form method="post" action="http://example.com/form">
<p>
<label for="name"> Name:
<input type="text" required id="name" name="name" />
</label>
</p><!--from w ww. jav a 2 s . c o m-->
<p>
<label for="password"> Password:
<input type="password" required placeholder="Min 6 characters" id="password"
name="password" />
</label>
</p>
<p>
<label for="accept">
<input type="checkbox" required id="accept" name="accept" /> Accept Terms & Conditions
</label>
</p>
<input type="submit" value="Submit" />
</form>
</body>
</html>