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Linux File Permissions

Every file and directory in Linux has permissions assigned to three categories:

1. User (Owner): A user is the owner of the file. By default, the person who created a file becomes its owner.
2. Group: A user- group can contain multiple users. All users belonging to a group will have the same Linux group permissions access to the file.
3. Others: Any other user who has access to a file.

Each category has three types of permissions:

• r (Read) → Can view the file contents
• w (Write) → Can modify the file

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// Move array element using splice where time complexity is Quadratic Time - O(n^2)
function arrayMove(arr, oldIndex, newIndex) {
  const copiedArr = [...arr];
  const length = copiedArr.length;
  
  if (oldIndex !== newIndex && length > oldIndex && length > newIndex) {
    copiedArr.splice(newIndex, 0, copiedArr.splice(oldIndex, 1)[0]);
  }
  
  return copiedArr;

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const getMouseEventCaretRange = (event, doc = document) => {
	const x = event.clientX;
	const y = event.clientY;

	// IE
	if (doc.body.createTextRange) {
		const range = doc.body.createTextRange();
		range.moveToPoint(x, y);
		return range;
	}

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1. Update the package repository

sudo apt update

2. Install NVM ^link

# using curl

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import React, {useState, useEffect} from 'react'

const Example = () => {
  const [user, setUser] = useState(null)
  const signal = axios.CancelToken.source()
  
  useEffect(() => {
    (async function loadUser(){
      try {
        const {data} = await axios.get('https://randomuser.me/api', {

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React

React.memo

const Greeting = ({ name }) => <div>Hello, {name}</div>
const MemoizedGreeting = React.memo(Greeting)

When a component is wrapped in React.memo(), React renders the component and memoizes the result. Before the next render, if the new props are the same, React reuses the memoized result skipping the next rendering.

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git

istall git:

sudo apt install git

curl

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this

1. Global Context

console.log(this) // Window {postMessage: ƒ, blur: ƒ, focus: ƒ, close: ƒ, parent: Window, …}

function printThis() {

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const board = ['#####B#', '##### #', '####  #', '#### ##', '     ##', 'A######']

class Node {
  constructor(state, parent, action) {
    this.state = state
    this.parent = parent
    this.action = action
  }
}

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import React from 'react'

const UserProfile = ({ data }) => {
  return (
    <>
      <h1>{data.name}</h1>
      <h2>{data.email}</h2>
    </>
  )
}