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

JavaScript is often described as an object-based language, meaning it is centered around objects. While it supports object-oriented programming (OOP) concepts, it is more accurate to describe it as object-based due to its prototypal inheritance model rather than classical inheritance.

Object-Based: JavaScript is built around objects and supports the creation and manipulation of objects.

Object-Oriented Features: JavaScript supports OOP principles like encapsulation, inheritance, and polymorphism, but through prototype chains rather than class-based inheritance.

Functional and Event-Driven: JavaScript supports functional programming and is often used in an event-driven manner, particularly in the context of web browsers.

References:

MDN Web Docs on JavaScript Object Model

W3C JavaScript Overview

Cascading Style Sheets (CSS) are used to control the presentation of web pages, including aspects such as layout, colors, fonts, and other visual styles. They are a cornerstone technology of the World Wide Web, along with HTML and JavaScript. Here’s a detailed breakdown:

Purpose of CSS: CSS is designed to enable the separation of document content (written in HTML or a similar markup language) from document presentation, including elements such as the layout, colors, and fonts. This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, enable multiple web pages to share formatting, and reduce complexity and repetition in the structural content.

Setting Visual Rules: CSS allows developers to define rules that specify how different elements of a web page should be displayed. For example, CSS rules can change text color, font size, spacing between elements, and even the overall layout of the web page. These rules are applied by the browser to render the web page according to the defined styles.

Cascading Nature: The term "cascading" in CSS refers to the process of combining multiple style sheets and resolving conflicts between different CSS rules. This allows developers to use different sources of style information, which can be combined in a hierarchical manner. For instance, a browser style sheet, an external style sheet, and inline styles can all contribute to the final rendering of a web page.

Benefits of CSS:

Consistency: By using CSS, developers can ensure a consistent look and feel across multiple web pages.

Maintainability: CSS makes it easier to update the visual presentation of a web page without altering the HTML structure. This is particularly useful for maintaining large websites.

Reusability: CSS rules can be reused across multiple pages, reducing redundancy and making it easier to implement changes globally.

Examples of CSS:

css

Copy code

body {

background-color: lightblue;

}

h1 {

color: navy;

margin-left: 20px;

}

In this example, the body element is given a light blue background color, and the h1 element is styled with a navy color and a left margin of 20 pixels.

References:

MDN Web Docs on CSS

W3C CSS Specifications

In JavaScript, the name of a function is defined after the function keyword and before the parentheses that enclose its parameters.

Function Name: The function name is the identifier used to call the function. It is defined immediately after the function keyword.

Usage Example:

function square(number) {

return number * number;

}

In this example, the name of the function is square.

References:

MDN Web Docs on Functions

ECMAScript Language Specification

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

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

The watchPosition method in the Geolocation API is used to get periodic updates about the geographic location of a user.

watchPosition Method: This method calls the provided callback function with the user's current position as the device's location changes.

Usage Example:

navigator.geolocation.watchPosition(function(position) {

console.log("Latitude: " + position.coords.latitude + ", Longitude: " + position.coords.longitude);

});

In this example, the watchPosition method continuously logs the user's latitude and longitude to the console as the position changes.

References:

MDN Web Docs on watchPosition

W3C Geolocation API Specification

The data type of the variable a is determined by the value assigned to it. In JavaScript, if a value is enclosed in double or single quotes, it is treated as a string.

Variable Assignment:

Given the code:

var a = "true";

The value "true" is enclosed in double quotes, making it a string.

Explanation:

Option A: Boolean is incorrect because the value "true" is a string, not a boolean.

Option B: String is correct because the value is enclosed in double quotes.

Option C: Object is incorrect because the value is a primitive string.

Option D: Undefined is incorrect because the variable a is assigned a value.

References:

MDN Web Docs - JavaScript Data Types

W3Schools - JavaScript Data Types