JavaScript Day 9 — Mastering JavaScript Basics: A Comprehensive Guide for Interview Preparation
100 Days of JavaScript Interview Prep: A Beginner’s Journey
Welcome to Day 9–100 Days of JavaScript Interview Prep: A Beginner’s Journey
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DAY 9 (March 31, 2024) —Primitive and Non-primitive Data Types Interview Questions
Question 1 : What are primitive data types in JavaScript?
Answer:
A primitive (primitive value, primitive data type) is data that is not an object and has no methods or properties.
There are 7 primitive data types
All primitives are immutable; that is, they cannot be altered
Number: let num = 10;
String: let str = "Hello";
Boolean: let bool = true;
Null: let nullValue = null;
Undefined: let undefinedValue;
Symbol: let sym = Symbol("foo");
BigInt
Question 2: Differentiate between primitive and non-primitive data types in JavaScript, with examples?
Answer
Primitive data types
- Primitive data types are immutable and stored directly in the variable, while non-primitive data types are mutable and stored by reference.
- Primitive values are stored directly in the variable’s memory location.
- Primitive Data Types: Passed by value. When passing a primitive value to a function, a copy of the value is passed.
- Primitive Data Types: Typically smaller and fixed.
Example of primitive type:
Primitive Data Types: Number, String, Boolean, Null, Undefined, Symbol.
let num = 10;
let str = "Hello world";Non-primitive data types
- Non-primitive data types are mutable.
- They can be modified after creation.
- Non-primitive values are stored by reference.
- Variables hold references (memory addresses) to the actual object stored in the heap
- Non-Primitive Data Types: Object (including arrays, functions, and other objects).
- Non-Primitive Data Types: Passed by reference. When passing a non-primitive value to a function, the reference to the original value is passed.
- Non-Primitive Data Types: Can vary in size based on the contents of the object and are dynamically resizable.
let employee= { name: "tommy", age: 23 };
let myNumbers= [1, 2, 3,4,5];Kind is cool !!! Share knowledge to gain knowledge !!!! Be kind and treat people with respect !!
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Kirti Kaushal
