JavaScript Certification Test Questions and Answers Already Passed

JavaScript Certification Test Questions
and Answers Already Passed
What does `typeof` do in JavaScript?


✔✔ It returns the data type of a value




How do you create a function in JavaScript?


✔✔ Using the `function` keyword or arrow syntax




What will `5 + "5"` return in JavaScript?


✔✔ `"55"` (string concatenation)




How do you convert a string to a number in JavaScript?


✔✔ Using `parseInt()`, `parseFloat()`, or `Number()`




What is an array in JavaScript?


✔✔ A collection of elements stored in square brackets




1

,How do you add an element to the end of an array?


✔✔ Using `push()`




How do you remove the last element from an array?


✔✔ Using `pop()`




What is the purpose of a loop in JavaScript?


✔✔ To repeat a block of code multiple times




How do you write a `for` loop in JavaScript?


✔✔ `for (let i = 0; i < 10; i++) {}`




What is an object in JavaScript?


✔✔ A collection of key-value pairs




How do you access a property of an object?


✔✔ Using dot notation or bracket notation




2

, What does `null` mean in JavaScript?


✔✔ It represents an intentional absence of value




What does `undefined` mean in JavaScript?


✔✔ A variable that has been declared but not assigned a value




How do you check if an array contains an element?


✔✔ Using `includes()`




What is JavaScript used for in web development?


✔✔ To create interactive and dynamic web pages




How do you declare a variable in JavaScript?


✔✔ Using `let`, `const`, or `var`




What keyword is used to define a constant variable?


✔✔ `const`




3