DEV Community: Muhammad Saim Hashmi

Last Index Value Of Array Javascript/TypeScript

Muhammad Saim Hashmi — Wed, 02 Nov 2022 04:46:49 +0000

Hey everyone, I usually give thought to how can I make my and other's life easy, so came up with the idea to write articles.
Getting to the point, I came across a life hack for arrays. Finding the last index value in an array was always like using the array's length and subtracting 1 from it(As the array gives length like normal daily like counting, whereas arrays start with 0 indexes).

Example

let array = [3,4,5,6,7];
let lastElement = array[array.length - 1];
console.log(lastElement); // prints 7

So whats the way around? Here it is 😁😁

let array = [3,4,5,6,7];
let lastElement = array.at(-1);
console.log(lastElement); //prints 7

Additionally
Just keep going reverse, you can get all elements of the array. Don't forget a condition to avoid going out of indexes as it'll give you undefined.

Feel free to comment to add more information to this article. Happy Coding.

Normal vs Shallow vs Deep Copy in Javascript/Typescript

Muhammad Saim Hashmi — Mon, 31 Oct 2022 05:01:07 +0000

Hey everyone, just like my last article on Difference between ? and ?? in JavaScript/Typescript, I am motivated to write again to contribute something to the community. Today, we'll talk about how object copies work in Javascript/Typescript with code snippets.

Before starting, I would recommend you guys to look closely at this topic. Why? Because this thing causes a hell of a pain in the neck when dealing with Nested Objects. So let's get started.

Normal Copy

Normal copy does not copy the value, but its instance or its memory address. If the copied instance value is updated, the original value is updated. Similar to static keyword in Java(If you know Java).

Example

const original = { x: 0 }
const normalCopy = original;
normalCopy.x = 1; // also updates original.x
console.log(original.x); //prints 1
console.log(normalCopy.x); //prints 1

Shallow Copy

Shallow copy copies the outermost object value and does not copy the nested objects. This means that the initial object values are copied while the nested ones are not copied by value but copied by reference.Ï

Example

const user = {
  name: "John",
  contact: {
    home: "+12345",
  }
}
const shallowCopy = { ...user };
shallowCopy.name = "John Smith";// updates its own copy
shallowCopy.contact.home = "+999";// updates both original and copy

console.log(user);
console.log(shallowCopy);
//Output
//https://dev-to-uploads.s3.amazonaws.com/uploads/articles/61n4uyvjpghid4kq0hdx.png

Deep Copy

A deep copy copies the entire object with its nested objects and creates a new clone of it in the memory.

Example

const user = {
  name: "John",
  contact: {
    home: "+12345",
  }
}
const shallowCopy = JSON.parse(JSON.stringify(user));
shallowCopy.name = "John Smith";
shallowCopy.contact.home = "+999";

console.log(user);
console.log(shallowCopy);
//Output
//https://dev-to-uploads.s3.amazonaws.com/uploads/articles/k7lb0jbhds7nzk8gwlkh.png

Thanks for reading this article. Please do comment so that I can improve my content. Happy Monday.

Difference between ? and ?? in JavaScript/Typescript

Muhammad Saim Hashmi — Wed, 26 Oct 2022 05:17:24 +0000

Hey folks, if you have opened this article that means you are curious about these 2 operators, how they operate, and what's the difference between these two. So without wasting any time, let's jump into details with a code example.

?

? is Optional Chaining Operator, also commonly named as null checker for objects. Its primary use is to check if an object exists or not.

Example

const user = {
    id: 5,
    name: "John"
};
console.log(user?.name); //John
console.log(user?.fullName); //undefined, program won't crash.
console.log(user.fullName); 
//TypeError: Cannot read property ‘fullName’ of undefined

??

?? is Nullish Coalescing Operator. It is used to initialize an object/variable if it is undefined or null.

Example

const user = {
    id: 5,
    name: "",
    firstName: null,
    lastName: undefined
};
console.log(user.name??"Johnny Depp");// prints ""
console.log(user.firstName??"Johnny");// prints Johnny
console.log(user.lastName??"Depp");// prints Depp

Feel free to add suggestions in the comments.
Thanks. Happy Coding.