Web-Development-Applications Questions and Answers

The pattern attribute in the element is used to define a regular expression that the input value must match for it to be valid. The pattern \d{5} ensures that the data entered is either a five-digit zip code or an empty string (if the required attribute is not used).

Pattern Explanation:

\d{5}: Matches exactly five digits.

This ensures that only a five-digit number or an empty string (if not required) is valid.

Usage Example:

This ensures that the input matches a five-digit zip code.

References:

MDN Web Docs on pattern

Regular Expressions Documentation

AJAX (Asynchronous JavaScript and XML) is used to request and update data in the background without reloading the web page.

AJAX Overview:

Purpose: Allows web pages to be updated asynchronously by exchanging data with a web server behind the scenes.

Benefits: Provides a smoother user experience by avoiding full page reloads.

Example:

Using XMLHttpRequest:

var xhr = new XMLHttpRequest();

xhr.open("GET", "data.json", true);

xhr.onreadystatechange = function() {

if (xhr.readyState === 4 && xhr.status === 200) {

var data = JSON.parse(xhr.responseText);

console.log(data);

}

};

xhr.send();

References:

MDN Web Docs - AJAX

W3Schools - AJAX Introduction

The element in HTML5 is used to render images and graphics dynamically through JavaScript. It is a powerful feature for creating graphics, game visuals, data visualizations, and other graphical content directly in the browser.

Canvas Element: The element is an HTML tag that, with the help of JavaScript, can be used to draw and manipulate graphics on the fly.

Usage Example:

In this example, a red rectangle is drawn on a canvas element.

References:

MDN Web Docs on

W3C HTML Canvas 2D Context Specification