Selecting Required and Optional input Elements
Description
The :required selector matches input elements that have the required attribute.
The :optional selector selects input elements that do not have the required attribute.
Example
The following code shows how to select Required and Optional input Elements.
<!DOCTYPE HTML>
<html>
<head>
<style>
:required {<!-- www . java 2 s . c o m-->
outline: medium solid green;
}
:optional {
outline: medium solid red;
}
</style>
</head>
<body>
<form method="post" action="http://example.com/form">
<p>
<label for="price1"> $ per unit in your area:
<input type="number" min="0" max="100" required value="1" id="price1" name="price1" />
</label>
<label for="price2"> $ per unit in your area:
<input type="number" min="0" max="100" value="1" id="price2" name="price2" />
<input type="submit" value="Submit" />
</label>
</p>
</form>
</body>
</html>