Forms in HTML — Interview Questions & Answers

Introduction to Forms

Ques: What are HTML forms used for?

Ans: Forms collect user input and send it to a server for processing.

Example:

<form action="/submit" method="post">
  <label>Name:</label>
  <input type="text" name="username">
  <input type="submit" value="Send">
</form>

Form Attributes

Attribute	Description	Example
`action`	Where to send form data	`<form action="/login">`
`method`	HTTP method (GET / POST)	`<form method="post">`
`target`	Where to display response	`_self`, `_blank`
`autocomplete`	Enables/disables auto-fill	`autocomplete="off"`
`novalidate`	Disables browser validation	`<form novalidate>`

Form Methods

Ques: What is the difference between GET and POST?

GET	POST
Appends data to URL	Sends data in body
Not secure	More secure
Used for fetching data	Used for submitting data
Limited data size	No size limit

Example using POST:

<form action="/register" method="post">
  <input type="text" name="user">
  <input type="submit" value="Register">
</form>

Form Controls

Tag	Purpose
`<input>`	Single-line input
`<textarea>`	Multi-line input
`<select>`	Dropdown menu
`<button>`	Clickable button
`<label>`	Describes input field
`<fieldset>` / `<legend>`	Group related fields

Input Types

Ques: List some common input types.

Ans: text, password, email, number, date, checkbox, radio, file, submit, reset, button, range, color.

Example:

<form>
  <input type="text" name="user" placeholder="Enter name"><br>
  <input type="password" name="pass"><br>
  <input type="email" name="email"><br>
  <input type="submit" value="Send">
</form>

Checkbox and Radio Buttons

Ques: How do you create checkboxes?

<input type="checkbox" name="hobby" value="music"> Music
<input type="checkbox" name="hobby" value="travel"> Travel

Ques: How do you create radio buttons?

<input type="radio" name="gender" value="male"> Male
<input type="radio" name="gender" value="female"> Female

Dropdowns and Text Areas

Ques: How do you create a dropdown menu?

<select name="country">
  <option value="in">India</option>
  <option value="us">USA</option>
  <option value="uk">UK</option>
</select>

Ques: How do you create a multi-line input field?

<textarea name="message" rows="4" cols="30"></textarea>

Labels and Accessibility

Ques: What is the purpose of <label>?

Ans: Improves accessibility by linking text to inputs.

<label for="email">Email:</label>
<input type="email" id="email">

Grouping Inputs

Ques: What are <fieldset> and <legend> used for?

<fieldset>
  <legend>Personal Info</legend>
  <input type="text" name="name">
  <input type="email" name="email">
</fieldset>

HTML5 Input Enhancements

Ques: List some new HTML5 input types.

Ans: date, time, number, range, color, email, url, tel.

Ques: What are some useful HTML5 attributes for validation?

Attribute	Purpose
`required`	Field must be filled
`min`, `max`	Limit values
`pattern`	Regex validation
`maxlength`	Max characters
`step`	Increment for numbers

Form Validation

Ques: How does HTML5 perform form validation?

Ans: Automatically checks built-in constraints before submission (e.g., required fields, pattern match).

Example:

<form>
  <input type="email" required>
  <input type="submit">
</form>

Buttons

Ques: What are the different button types?

Type	Action
`submit`	Submits form
`reset`	Clears form
`button`	Custom JS action

Example:

<button type="submit">Send</button>
<button type="reset">Clear</button>

File Upload

Q18: How to upload a file in HTML?

<form enctype="multipart/form-data">
  <input type="file" name="resume">
</form>

enctype="multipart/form-data" is required for file uploads.

Hidden Fields

Ques: What is the purpose of hidden inputs?

Ans: To store data not visible to users (e.g., user IDs).

<input type="hidden" name="userid" value="1234">

Advanced Form Features

Ques: How to auto-fill suggestions in inputs?

<input list="browsers">
<datalist id="browsers">
  <option value="Chrome">
  <option value="Firefox">
  <option value="Edge">
</datalist>

Ques: Is HTML form validation enough for security?

Ans: No, you must always validate on the server side too.

Ques: Why shouldn’t you use GET for password forms?

Ans: Because data appears in the URL and can be logged or cached.

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