HTML Interview Questions and Answers for 10 Years Experience

Question: What is the <form> tag used for in HTML?

Answer:

The <form> tag in HTML is used to define an HTML form that allows users to submit data to a server for processing. Forms are essential for capturing user input on websites, such as login details, search queries, or contact information.

---

Key Points about the <form> tag:

1. Basic Syntax: The <form> tag wraps form elements (such as text fields, buttons, checkboxes, and radio buttons) and handles the submission of data to a server.

   <form action="/submit_form" method="POST">
     <label for="name">Name:</label>
     <input type="text" id="name" name="name">
     <input type="submit" value="Submit">
   </form>

2. Attributes of the <form> Tag:

   • action: Specifies the URL to which the form data will be sent when the form is submitted. It defines the server endpoint that will process the form data.

     <form action="/submit_form" method="POST">

   • method: Defines the HTTP method used to send the form data. Common methods are:

     • GET: Appends the form data to the URL (suitable for search forms).
     • POST: Sends the form data in the body of the request (preferred for sensitive data like passwords or large data).

     <form action="/submit_form" method="POST">

   • name: Assigns a name to the form. This can be useful when manipulating the form with JavaScript.

     <form name="contactForm" action="/submit_form" method="POST">

   • target: Specifies where to display the response after form submission. Common values are:

     • _self: Opens the response in the same frame or window (default).
     • _blank: Opens the response in a new window or tab.
     • _parent and _top: Used for frames.

   • enctype: Specifies how the form data should be encoded when submitting it to the server. Common values are:

     • application/x-www-form-urlencoded: The default encoding, which sends form data as a query string.
     • multipart/form-data: Used when the form contains file inputs (e.g., for file uploads).
     • text/plain: Sends the form data as plain text.

---

Form Elements Inside a <form>:

1. Input Fields: Various input elements, such as text fields, radio buttons, checkboxes, and file upload fields, are used within forms to collect user input.

   <form action="/submit_form" method="POST">
     <input type="text" name="username" placeholder="Enter username">
     <input type="password" name="password" placeholder="Enter password">
   </form>

2. Submit Button: A submit button allows users to send the form data to the server.

   <input type="submit" value="Submit">

3. Select Dropdowns: The <select> element is used to create dropdown menus within the form.

   <select name="country">
     <option value="us">United States</option>
     <option value="ca">Canada</option>
   </select>

4. Textarea: The <textarea> element is used for multi-line text input.

   <textarea name="message" rows="4" cols="50" placeholder="Your message"></textarea>

5. Labels: The <label> element is used to define labels for form elements, improving accessibility.

   <label for="name">Name:</label>
   <input type="text" id="name" name="name">

---

Form Submission:

When the user submits the form (typically by pressing the submit button), the form data is sent to the server specified in the action attribute using the method defined in the method attribute. The server then processes the data and typically returns a response, such as a confirmation or error message.

---

Example of a Simple Form:

<form action="/submit_form" method="POST">
  <label for="email">Email:</label>
  <input type="email" id="email" name="email" required>
  <br>
  <label for="message">Message:</label>
  <textarea id="message" name="message" rows="4" required></textarea>
  <br>
  <input type="submit" value="Submit">
</form>

• action="/submit_form": The form will send data to the /submit_form endpoint.
• method="POST": The data will be sent as a POST request.
• required: Ensures the user cannot submit the form without filling in the email and message fields.

---

Summary:

The <form> tag in HTML is crucial for collecting and submitting user input. It wraps form elements and specifies how the data is sent to the server, through attributes like action, method, and enctype. Forms are fundamental to web applications, enabling users to interact with the website by sending data, such as through login forms, registration forms, search bars, and more.

Question: What is the difference between GET and POST methods in a form?

Answer:

The GET and POST methods are two common HTTP methods used to send data from a client (browser) to a server when submitting a form. They differ in how the data is sent and how it is processed by the server.

---

Key Differences Between GET and POST Methods:

1. Data Transmission Location:

   • GET: The data is sent appended to the URL in the query string. It is visible in the browser’s address bar.
     • Example: http://example.com/search?query=HTML&sort=asc
     • Use Case: Typically used for requests that do not modify server data, such as retrieving information or performing searches.
   • POST: The data is sent in the body of the HTTP request and is not visible in the URL.
     • Example: Form data (like a password) is sent securely in the body of the POST request.
     • Use Case: Commonly used for submitting data that will change server state, such as login credentials, form submissions, and file uploads.

2. Data Length:

   • GET: There is a limit on the amount of data that can be sent (typically around 2048 characters, depending on the browser).
   • POST: There is no specific limit to the size of the data that can be sent (limited only by server settings or hardware).

3. Security:

   • GET: Since the data is visible in the URL, it is not secure and should never be used for sensitive information like passwords or personal details.
   • POST: The data is sent in the body of the request, making it more secure compared to GET (although still not encrypted unless using HTTPS).

4. Caching:

   • GET: Since GET requests are considered idempotent (they don’t alter the server’s state), browsers may cache the responses, making them faster for repeated requests.
   • POST: POST requests are generally not cached because they are used to send data that changes the server’s state.

5. Bookmarking:

   • GET: Since GET parameters are included in the URL, the request can be bookmarked and revisited later by saving the URL.
     • Example: http://example.com/search?query=HTML
   • POST: Since POST data is not visible in the URL, POST requests cannot be bookmarked.

6. Idempotency:

   • GET: GET requests are idempotent, meaning that making the same GET request multiple times will not change the server’s state. They are safe for retrieving data.
   • POST: POST requests are not idempotent, meaning submitting the same form multiple times can result in different outcomes, such as creating multiple records in a database.

---

Summary Table:

Feature	GET	POST
Data Location	In the URL (query string)	In the request body
Data Size	Limited (approx. 2048 characters)	No specific limit
Visibility	Data is visible in the browser’s address bar	Data is not visible in the browser’s address bar
Security	Not secure (data visible in URL)	More secure (data not visible in URL)
Caching	Can be cached	Not cached
Bookmarking	Can be bookmarked	Cannot be bookmarked
Idempotency	Idempotent (safe for retrieval)	Not idempotent (used for modifying data)
Use Case	Retrieving data, such as search queries	Submitting forms, login credentials, file uploads

---

When to Use GET vs. POST:

• Use GET when:
  • Retrieving data from the server (e.g., searching for a product).
  • The data is not sensitive and is meant to be visible or shareable (e.g., search queries, filters).
  • The request should be idempotent and potentially cached.
• Use POST when:
  • Submitting sensitive data (e.g., login credentials, passwords, personal information).
  • The data modifies server state (e.g., submitting a contact form, making a purchase).
  • The amount of data to be sent is large or complex.

---

Example:

GET Example:

<form action="search.php" method="GET">
  <label for="query">Search:</label>
  <input type="text" id="query" name="query">
  <input type="submit" value="Search">
</form>

• URL after submission: http://example.com/search.php?query=HTML

POST Example:

<form action="submit.php" method="POST">
  <label for="username">Username:</label>
  <input type="text" id="username" name="username">
  <label for="password">Password:</label>
  <input type="password" id="password" name="password">
  <input type="submit" value="Login">
</form>

• Data sent securely in the body of the request.

---

Conclusion:

• GET is best suited for simple data retrieval and non-sensitive operations, where visibility and caching are important.
• POST is more suitable for operations that involve sensitive data or changes to the server state, where security and data size are primary concerns.

Read More

If you can’t get enough from this article, Aihirely has plenty more related information, such as HTML interview questions, HTML interview experiences, and details about various HTML job positions. Click here to check it out.