JavaScript Interview Questions for Freshers. If you’re preparing for your first job in web development, mastering JavaScript is essential. Whether you’re applying for a front-end role or full-stack position, most interviews will include a round focused on JavaScript interview.
This blog will guide you through the top most frequently asked JavaScript questions, complete with beginner-friendly answers to help you ace your interview.
Why Learn JavaScript?
JavaScript is the backbone of modern web development. It’s used to create dynamic, interactive websites and applications. With the rise of frameworks like React, Angular, and Node.js, JavaScript has become an all-in-one solution for client-side and server-side development.
JavaScript Interview Questions for Freshers (With Answers)
What is JavaScript?
JavaScript is a lightweight, interpreted scripting language mainly used to create interactive effects within web browsers. It’s an essential part of web development alongside HTML and CSS.
What are the different data types in JavaScript?
JavaScript has the following basic data types:
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String
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Number
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Boolean
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Null
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Undefined
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Object
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Symbol (introduced in ES6)
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BigInt (introduced in ES2020)
What is the difference between == and ===?
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==checks for value equality (loose comparison) and performs type conversion. -
===checks for both value and type equality (strict comparison).
Example:
What are variables in JavaScript?
Variables are containers used to store data values. JavaScript uses var, let, and const to declare variables.
What is the difference between var, let, and const?
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var: function-scoped, can be redeclared. -
let: block-scoped, cannot be redeclared. -
const: block-scoped, used for constants (cannot be reassigned or redeclared).
What is an array in JavaScript?
An array is a special variable that can hold multiple values.
Example:
What is a function in JavaScript?
A function is a block of reusable code designed to perform a specific task.
Example:
What is a callback function?
A callback is a function passed as an argument to another function. It is commonly used in asynchronous programming.
Example:
What is an object in JavaScript?
Objects are collections of key-value pairs used to store multiple values in a single variable.
Example:
What is the DOM?
The Document Object Model (DOM) represents the structure of a web page. JavaScript can manipulate the DOM to update content dynamically.
What is the difference between null and undefined?
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null: A value that represents “no value”. -
undefined: A variable that has been declared but has not yet been assigned a value.
What is hoisting in JavaScript?
Hoisting is JavaScript’s default behavior of moving declarations to the top of the scope.
Example:
What is the use of this keyword?
this refers to the object that is currently executing the function.
What is an event in JavaScript?
An event is an action that occurs in the browser, such as a mouse click or key press. JavaScript can be used to handle these events.
What are arrow functions in JavaScript?
Arrow functions provide a shorter syntax to write functions and do not have their own this.
Arrow functions and traditional functions in JavaScript differ in both syntax and behavior, particularly in how they handle the this keyword and the arguments object. Arrow functions are typically shorter and ideal for one-liner expressions, as they inherit this from their surrounding context. In contrast, regular functions have their own this context determined at runtime
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