Common HTML Events Quiz

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Questions and Answers

What will be the value of x after the JavaScript operation 'let x = 100 + 50;'?

150 (correct)

1050

10050

What will be displayed when the following JavaScript code is executed: 'document.getElementById("demo").innerHTML = (5 == "5");'?

true (correct)

NaN

false

What does the JavaScript Bitwise XOR (^) operator do?

Always returns 1

Performs a logical AND operation

Performs a logical OR operation

Returns a 1 in each bit position if both bits are 1, otherwise 0 (correct)

In JavaScript, what does the Logical AND (&&) operator return?

True if both expressions are true, false otherwise Signup and view all the answers

What does the 'countDown(4)' function in JavaScript do?

Counts down numbers from 4 to 1 recursively Signup and view all the answers

Why do developers use JavaScript events?

To execute code when specific actions occur in a webpage Signup and view all the answers

Which JavaScript feature introduced in ES6 allows for creating functions in a cleaner way compared to regular functions?

Arrow functions Signup and view all the answers

In JavaScript, what does the following arrow function do? `let myFunction = (arg1, arg2) => arg1 + arg2;`

Adds arg1 and arg2 Signup and view all the answers

What is the purpose of the 'changeColorOnMouseOut' function in JavaScript?

Change background color on mouseout Signup and view all the answers

In JavaScript, what is the role of the 'add()' function in the provided example?

To add two numbers Signup and view all the answers

Which of the following JavaScript features is used to execute a script immediately after a page has been loaded?

'document.write' Signup and view all the answers

What is the purpose of the 'changeColorOnMouseOver' function in the JavaScript example?

Change background color on mouseover Signup and view all the answers

How is an object property accessed using dot notation in JavaScript?

objectName.key Signup and view all the answers

What is the correct syntax to declare an object in JavaScript?

const object_name = { key1: value1, key2: value2 } Signup and view all the answers

Which notation should be used to access an object property in JavaScript if the key contains a space?

objectName['key'] Signup and view all the answers

What happens if you try to access an object method in JavaScript without parentheses?

It will return the function definition Signup and view all the answers

In JavaScript, how can you access an object method?

objectName.methodKey() Signup and view all the answers

What is the purpose of using bracket notation to access an object property in JavaScript?

To avoid conflicts with reserved keywords Signup and view all the answers

Study Notes

JavaScript Basics

The value of x after the operation let x = 100 + 50; will be 150.
The expression document.getElementById("demo").innerHTML = (5 == "5"); returns true because the equality operator (==) performs type coercion, considering both values equal.

Operators in JavaScript

The Bitwise XOR (^) operator compares two bits and returns 1 for a bit if only one of the bits is 1; returns 0 otherwise.
The Logical AND (&&) operator returns true if both operands are true; otherwise, it returns false.

Functions and Events

The countDown(4) function is typically designed to count down from 4 to 0, possibly executing code for each number in the sequence.
Developers utilize JavaScript events to create interactive experiences on web pages, responding to user actions like clicks and key presses.
ES6 introduced arrow functions, allowing a more concise syntax for writing functions compared to traditional function expressions.

Arrow Functions and Object Manipulation

The arrow function let myFunction = (arg1, arg2) => arg1 + arg2; takes two arguments and returns their sum, simplifying function definition.
The purpose of the changeColorOnMouseOut function is usually to revert the color of an element when the mouse pointer leaves it.

Object Functions and Notation

The add() function in a JavaScript example typically performs an operation like adding numerical values or combining data types.
The DOMContentLoaded event is used to execute a script immediately after a page has loaded, ensuring the DOM is fully constructed before running scripts.

Dot and Bracket Notation

Dot notation accesses object properties using the syntax objectName.propertyName, making it straightforward to retrieve values.
To declare an object in JavaScript, the syntax is let objectName = { key: value };.
Bracket notation is necessary to access object properties when keys contain spaces, using objectName["key with space"].

Method Access

If an object method is accessed without parentheses, it references the function itself instead of invoking it, leading to the function not executing.
An object method is accessed by calling it with parentheses, such as objectName.methodName().
Bracket notation is useful for dynamic access to object properties, particularly when keys are stored in variables.

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Description

Test your knowledge of common HTML events with this quiz. Learn about how to execute JavaScript functions and events in HTML, such as triggering a function after a page loads or changing styles on mouseover.