HTML5: How to specify that an input field must be filled out before submitting the form?

Last update on February 09 2024 12:52:41 (UTC/GMT +8 hours)

Solution :

HTML Code:

<!DOCTYPE html><!-- Declares the document type and version of HTML -->
<html>
<head>
<meta charset="utf-8"><!-- Specifies the character encoding for the document -->
<title>How to specify that an input field must be filled out before submitting the form</title><!-- Sets the title of the document -->
</head>
<body>
<form method="post" <!-- Begins a form element with the method attribute set to "post", indicating that form data will be submitted via HTTP POST method -->
action="https://www.w3resource.com/html-css-exercise/basic/solution/input-required-answer-demo.php"><!-- Specifies the URL where the form data will be sent upon submission -->
Telephone No: <input type="number" name="phone_no" required><!-- Creates a number input field for entering the telephone number. The name attribute is set to "phone_no" to identify the input data on the server side. The required attribute specifies that the input field must be filled out before submitting the form -->
<input type="submit"><!-- Creates a submit button within the form -->
</form>
</body>
</html>

Explanation:

The HTML document starts with a declaration of its type and version (<!DOCTYPE html>).
The <html> element encloses the entire HTML document.
The <head> section contains metadata about the document, including the character encoding (<meta charset="utf-8">) and the title of the document (<title>).
Within the <body> section, a <form> element is used to create a form for user input. The method attribute is set to "post", indicating that form data will be submitted via HTTP POST method, and the action attribute specifies the URL where the form data will be sent upon submission.
Inside the form, there's an <input> element with type "number" for entering the telephone number. The name attribute is set to "phone_no" to identify the input data on the server side.
The input field also includes the required attribute, which specifies that the input field must be filled out before submitting the form.
Finally, an <input> element with type "submit" is used to create a submit button within the form, allowing users to submit the form data.

Live Demo:

See the Pen input-required-answer by w3resource (@w3resource) on CodePen.

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