JavaScript

How do you convert a string to an integer in JavaScript? a) parseInt() b) parseFloat() c) Number() d) toString() Answer: a) parseInt() Explanation: The parseInt() function converts a string to an integer by parsing the string and returning the first integer value found. If the string does not contain a number, NaN (Not-a-Number) is returned. […]

What is the purpose of the Math.random() method in JavaScript? a) To generate a random number between 0 and 1 b) To round numbers to the nearest integer c) To generate a random integer d) To find the square root of a number Answer: a) To generate a random number between 0 and 1 Explanation:

How do you check if a variable is an array in JavaScript? a) Array.isArray(variable) b) variable.isArray() c) typeof variable === “array” d) variable instanceof Array Answer: a) Array.isArray(variable) Explanation: The method Array.isArray() is used to determine whether a variable is an array. It returns true if the variable is an array, and false otherwise. Example:

What is the output of the following code: console.log(typeof null);? a) “object” b) “null” c) “undefined” d) “boolean” Answer: a) “object” Explanation: In JavaScript, the typeof operator returns “object” when applied to null. This is considered a quirk in JavaScript, as null is generally treated as a separate data type. Example: console.log(typeof null); // Output:

What is the purpose of the return statement in JavaScript? a) To exit a function and return a value b) To stop a loop c) To repeat a function d) To declare a variable Answer: a) To exit a function and return a value Explanation: The return statement is used inside a function to stop

How do you write a function expression in JavaScript? a) let myFunction = function() { … } b) function = myFunction() { … } c) def myFunction() { … } d) fn myFunction() { … } Answer: a) let myFunction = function() { … } Explanation: In JavaScript, a function expression is a function assigned

What is the use of Array.length in JavaScript? a) To find the number of elements in an array b) To remove elements from an array c) To sort elements in an array d) To add elements to an array Answer: a) To find the number of elements in an array Explanation: The Array.length property returns

How do you create a loop in JavaScript that runs 5 times? a) for (let i = 0; i < 5; i++) { … } b) while (i < 5) { … } c) for (i <= 5) { … } d) loop (i < 5) { … } Answer: a) for (let i =

What is the output of the following code: console.log(5 == “5”);? a) true b) false c) NaN d) undefined Answer: a) true Explanation: In JavaScript, the double equals == performs type coercion, meaning it converts the operands to the same type before comparing. Here, "5" (a string) is converted to 5 (a number), so the

What is the purpose of the Array.push() method in JavaScript? a) To add elements to the end of an array b) To remove elements from the array c) To sort the elements in an array d) To find the length of an array Answer: a) To add elements to the end of an array Explanation:

What is the output of the following code: console.log(“5” + 5);? a) “55” b) 10 c) NaN d) 5 Answer: a) “55” Explanation: When you use the + operator between a string and a number, JavaScript performs string concatenation. In this case, “5” (a string) is concatenated with 5 (a number), resulting in “55” (a

Which of the following is the correct way to define an object in JavaScript? a) var obj = { key: value }; b) var obj = [ key, value ]; c) var obj = “key = value”; d) var obj = (key, value); Answer: a) var obj = { key: value }; Explanation: In JavaScript,

How do you create an array in JavaScript? a) var arr = []; b) let arr = Array; c) var arr = {}; d) let arr = newList(); Answer: a) var arr = []; Explanation: In JavaScript, arrays are created using square brackets []. The elements are separated by commas. Example: var fruits = ["Apple",

What is the correct way to write a function in JavaScript? a) function myFunction() { … } b) func myFunction() { … } c) def myFunction() { … } d) fn myFunction() { … } Answer: a) function myFunction() { … } Explanation: In JavaScript, functions are declared using the function keyword followed by the

How do you write a conditional statement in JavaScript? a) if (condition) { … } b) check (condition) { … } c) when (condition) { … } d) condition (if) { … } Answer: a) if (condition) { … } Explanation: In JavaScript, a conditional statement is written using if. It checks a condition and

What is the output of the following code: console.log(typeof 42);? a) “number” b) “string” c) “boolean” d) “undefined” Answer: a) “number” Explanation: The typeof operator is used to determine the data type of a given variable or value in JavaScript. In this case, 42 is a number, so the output is “number”. Example: console.log(typeof 42);

Which of the following is used to output data to the browser console in JavaScript? a) console.output() b) console.log() c) output.console() d) browser.log() Answer: b) console.log() Explanation: To output data to the browser’s console, you use the console.log() method in JavaScript. This is useful for debugging and displaying information during development. Example: console.log("Hello, World!"); Reference:

How do you declare a variable in JavaScript? a) var, let, const b) int, float, double c) String, Number, Boolean d) define, declare, constant Answer: a) var, let, const Explanation: In JavaScript, you can declare variables using var, let, or const. Each keyword has a different scope and behavior. var is function-scoped, while let and

Which of the following is the correct way to write a comment in JavaScript? a) # This is a comment b) // This is a comment c) d) /* This is a comment */ Answer: b) // This is a comment Explanation: In JavaScript, single-line comments are written using // at the beginning of the

What is JavaScript? a) A programming language for web development b) A type of hardware c) A database language d) A styling language Answer: a) A programming language for web development Explanation: JavaScript is a popular programming language used primarily for web development. It allows developers to create dynamic content and interactive elements in web