What is the purpose of the "push()" method in JavaScript?

To add elements to the end of an array

What is the purpose of the "forEach()" method in JavaScript?

To iterate over elements in an array

What is the purpose of the "typeof" operator in JavaScript?

Determine the type of a variable

What is the use of the "querySelector()" method in JavaScript?

To select the first element that matches a CSS selector

Difference between "let" and "const" in JavaScript?

"let" for reassignable block scope

What is the difference between "==" and "===" in JavaScript?

"===" performs loose equality comparison

Difference between synchronous and asynchronous JavaScript

Sequential execution, no blocking

Difference between "null" and "undefined" in JavaScript?

"null" represents intentional absence

What is the difference between "const" and "let" in JavaScript?

"const" variables cannot be reassigned

What is event delegation in JavaScript?

Single event listener on parent element

What is the purpose of the "slice()" method in JavaScript?

To extract a portion of an array

What is the difference between "let" and "var" in JavaScript?

"let" has block scope, "var" has function scope

What is the purpose of the Array.prototype.map() method?

To transform each element of an array

What is the purpose of the "reduce()" method in JavaScript?

To combine elements in an array

What are closures in JavaScript?

Functions with access to outer variables

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Kenyan Quiz 4

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Questions 25

Answers

1
Purpose of the "this" keyword in JavaScript?
Define conditional statements
Create new object instances
Declare variables
Refers to the executing object
2
What is the purpose of the "push()" method in JavaScript?
To remove elements from an array
To add elements to the beginning of an array
To reverse the order of elements in an array
To add elements to the end of an array
3
How do you declare a function in JavaScript?
function myFunction() {}
var myFunction = function() {}
const myFunction = () => {}
All of the above
4
How does JavaScript handle errors?
Using try-catch statements
Ignoring errors
Using if-else statements
Displaying errors in the console
5
How do you declare a constant variable in JavaScript?
By using the "const" keyword
By using the "var" keyword
By using the "let" keyword
By using the "if" statement
6
What is the purpose of the "forEach()" method in JavaScript?
To iterate over elements in an array
To filter elements in an array
To combine elements in an array
To sort elements in an array
7
What is the purpose of the "typeof" operator in JavaScript?
Perform mathematical operations
Determine the type of a variable
Control the flow of execution
Create new variables
8
What is the result of the expression "typeof null" in JavaScript?
"undefined"
"Error"
"object"
"null"
9
What is the use of the "querySelector()" method in JavaScript?
To select the first element that matches a CSS selector
To select the parent element of a given element
To select all elements that match a CSS selector
To select the last element that matches a CSS selector
10
Difference between "let" and "const" in JavaScript?
"const" for non-reassignable block scope
"let" for reassignable block scope
"let" for function scope, "const" for block scope
"let" for constant values, "const" for reassignable values
11
What does the "NaN" value represent in JavaScript?
Not a Number
Negative Number
Null
No Argument
12
What is the difference between "==" and "===" in JavaScript?
"==" performs strict equality comparison
"===" performs loose equality comparison
"==" compares values, "===" compares values and types
"==" is used for strings, "===" is used for numbers
13
Difference between synchronous and asynchronous JavaScript
Sequential execution, no blocking
Server-side vs. client-side
Concurrent execution, blocking
Front-end vs. back-end
14
Difference between "null" and "undefined" in JavaScript?
"undefined" is unassigned
"null" is unassigned, "undefined" represents absence
"null" represents intentional absence
Both are error values
15
How do you convert a string to a number in JavaScript?
By using the parseNumber() method
By using the Number() function
By using the convertToNumber() function
By using the toNumber() method
16
What is the difference between "const" and "let" in JavaScript?
"let" variables cannot be reassigned
"const" variables have block scope
"const" variables cannot be reassigned
"let" variables have block scope
17
What is event delegation in JavaScript?
Handling errors
Implementing object-oriented programming
Single event listener on parent element
Binding event listeners to multiple elements
18
What is the result of the expression "10 + '20'" in JavaScript?
"102020"
"Error"
"30"
"1020"
19
What is the purpose of the "slice()" method in JavaScript?
To extract a portion of an array
To remove elements from an array
To reverse the order of elements in an array
To add elements to an array
20
How do you check if a variable is an array in JavaScript?
By using the typeof operator
By using the isArray() method
By converting it to a string
By checking the length property
21
What is the difference between "let" and "var" in JavaScript?
"let" is modern, "var" is outdated
"let" has block scope, "var" has function scope
"let" is used for constants, "var" is used for variables
"let" allows redeclaration, "var" does not
22
How do you add a comment in JavaScript?
// This is a comment
// This is a comment //
/* This is a comment */
23
What is the purpose of the Array.prototype.map() method?
To transform each element of an array
To remove elements from an array
To add elements to an array
To sort the elements of an array
24
What is the purpose of the "reduce()" method in JavaScript?
To sort elements in an array
To combine elements in an array
To iterate over elements in an array
To filter elements in an array
25
What are closures in JavaScript?
Objects storing multiple values
Functions with access to outer variables
JavaScript modules
Built-in array methods

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