Web-Development-Applications Exam Dumps - WGU Courses and Certificates Questions and Answers

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

JavaScript form validation typically occurs after the form is submitted but before the form data is sent to the server. This allows the client-side script to check the input data and prevent the form from being submitted if the data is invalid.

Client-Side Validation:

Before Form Submission: JavaScript validates the form fields after the user attempts to submit the form.

Prevent Default Submission: If the validation fails, JavaScript can prevent the form from being submitted and display appropriate error messages.

Usage Example:

document.getElementById("myForm").addEventListener("submit", function(event) {

var isValid = true;

// Perform validation checks

if (!isValid) {

event.preventDefault(); // Prevent form submission

alert("Please correct the errors.");

}

});

This example prevents form submission if the validation fails.

References:

MDN Web Docs on Form Validation

W3C HTML Specification on Form Submission

The CSS transition-delay property specifies how long to wait before starting a property transition. In the given CSS code, the transition-delay is set to 2s.

CSS Transition Properties:

transition-property: Specifies the CSS property to which the transition is applied (font-size in this case).

transition-duration: Specifies how long the transition takes (4s).

 transition-delay: Specifies the delay before the transition starts (2s).

 Example:

Given HTML:

Given CSS:

#delay {

font-size: 14px;

transition-property: font-size;

transition-duration: 4s;

transition-delay: 2s;

}

#delay:hover {

font-size: 36px;

}

 Explanation: When a user hovers over the element with id="delay", it will wait for 2 seconds before the transition effect on font-size starts.

 References:

MDN Web Docs - transition-delay

W3C CSS Transitions

In JavaScript, curly braces {} are used to enclose multiple statements in a function, defining the block of code to be executed.

Curly Braces: Curly braces {} are used to group multiple statements into a single block. This is necessary for defining the body of a function, loops, conditional statements, and other control structures.

Usage Example:

function greet(name) {

let greeting = "Hello, " + name;

console.log(greeting);

}

In this example, the curly braces enclose the statements that form the body of the greet function.

References:

MDN Web Docs on Functions

ECMAScript Language Specification