Introduction
Gearing up for your first JavaScript interview? We’ve got you covered! From knowing the difference between Java and JavaScript to answering questions on data types and JavaScript functions, this blog contains the top JavaScript interview questions for freshers.
JavaScript Interview Questions for Beginners
1. What are the differences between Java and JavaScript?
| Aspect | Java | JavaScript |
|---|---|---|
| Type | Statically typed (compiled) | Dynamically typed (interpreted) |
| Platform | Runs on a virtual machine or browser | Runs only in browsers |
| Syntax | Class-based | Prototype-based |
| Compilation | Requires compilation | All code is in text (interpreted) |
| Purpose | General-purpose language | Primarily used for web interactivity |
| OOP | Strongly object-oriented | Object-oriented scripting |
| Features | Abstraction, encapsulation, inheritance, polymorphism | DOM manipulation, event handling, AJAX |
| Memory Management | Explicit memory allocation | Automatic garbage collection |
| Security | Strongly typed, secure | Less secure due to dynamic nature |
2. What are JavaScript Data Types?
Data types can be divided into primitive and non-primitive types. Primitive data types are further divided into:
String: Represents text and is enclosed in quotes (single or double).
var str = "Vivek Singh Bisht"; //using double quotes
var str2 = 'John Doe'; //using single quotes Number: Stores decimal numbers (floating point) and can include or exclude decimals.
var x = 3; //without decimal
var y = 3.6; //with decimal Bigint: Used for large integers.
var bigInteger = 234567890123456789012345678901234567890; Boolean: Represents true or false values.
var a = 2;
var b = 3;
var c = 2;
(a == b) // returns false
(a == c) //returns true Undefined: Indicates a variable that has been declared but not assigned a value.
var x; // value of x is undefined
var y = undefined; // we can also set the value of a variable as undefined Null: Represents the absence of any value.
var z = null; Symbol: Used for unique identifiers (introduced in ECMAScript 6).
var symbol1 = Symbol('symbol');Non-primitive data types are used to store multiple and complex values. Object data type is used to store the collection of non-primitive data.
3. Which symbol is used for comments in JavaScript?
In JavaScript, the double forward slash (//) is used for single-line comments. Anything after // on the same line is considered a comment and is ignored by the interpreter. For multi-line comments, you can use /* to start the comment block and */ to end it.
4. What would be the result of 3+2+”7″?
3 and 2 behave like an integer, and “7” behaves like a string. So 3 plus 2 will be 5. Then the output will be 5+”7″ = 57.
5. What is the use of the isNaN function?
JavaScript Interview Questions for Beginners
Enhance your JavaScript skills with our comprehensive collection of interview questions for beginners. Get ready to ace your next JavaScript interview!
PublishedMay 24, 2024
CategoryInterview Questions
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