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Why My Javascript random selector not working?

I want some help on this problem. I'm trying to get my JavaScript to highlight random picks that I enter in but its not working.
I keep getting a error message when I inspect my JS code on the webpage saying
"Uncaught TypeError: Cannot read properties of undefined (reading 'classList')
at highlightTag (script.js:52:9)
at script.js:38:9"
Here's the all the code below:
const tagsEl = document.getElementById('tags')
const textarea = document.getElementById('textarea')
textarea.focus()
textarea.addEventListener('keyup', (e) => {
createTags(e.target.value)
if (e.key === 'Enter') {
setTimeout(() => {
e.target.value = ''
}, 10)
randomSelect()
}
})
function createTags(input) {
const tags = input.split(',').filter(tag => tag.trim() !==
'').map(tag => tag.trim())
tagsEl.innerHTML = ''
tags.forEach(tag => {
const tagEl = document.createElement('span')
tagEl.classList.add('tag')
tagEl.innerText = tag
tagsEl.appendChild(tagEl)
})
}
function randomSelect() {
const times = 30
const interval = setInterval(() => {
const randomTag = pickRandomTag()
highlightTag(randomTag)
setTimeout(() => {
unHighlightTag(randomTag)
}, 100)
}, 100);
}
function pickRandomTag() {
const tags = document.querySelectorAll('.tag')
return tags[Math.floor(Math.random() * tags.length)]
}
function highlightTag(tag) {
tag.classList.add('hightlight')
}
function unHighlightTag(tag) {
tag.classList.remove('hightlight')
}
* {
box-sizing: border-box;
}
body {
background-color: #2b88f0;
font-family: 'Roboto', sans-serif;
display: flex;
flex-direction: column;
align-items: center;
justify-content: center;
height: 100vh;
overflow: hidden;
margin: 0;
}
h3 {
color: #fff;
margin: 10px 0 20px;
text-align: center;
}
.container {
width: 500px;
}
textarea {
border: none;
display: block;
width: 100%;
height: 100px;
font-family: inherit;
padding: 10px;
margin: 0 0 20px;
font-size: 16px;
}
.tag {
background-color: #f0932b;
color: #fff;
border-radius: 50px;
padding: 10px 20px;
margin: 0 5px 10px 0;
font-size: 14px;
display: inline-block;
}
.tag.highlight {
background-color: #273c75;
}
<link href="https://fonts.googleapis.com/css2?family=Roboto&display=swap&ext=.css" rel="stylesheet" />
<div class="container">
<h3>Enter all of the choices divided by a comma (','). <br> Press Enter when you are done</h3>
<textarea placeholder="Enter choices here..." id="textarea"></textarea>
<div id="tags">
</div>
</div>
<script src="script.js"></script>

The problem here is you keep creating intervals. So you have an instance where you remove the element and the random code is trying to select them. It finds nothing and you have your problem. You need to cancel the intervals when you alter the tags and you should look to see if an element exists before you try to reference it if you are going to use innerHTML to make new tags.
const tagsEl = document.getElementById('tags')
const textarea = document.getElementById('textarea')
textarea.focus()
textarea.addEventListener('keyup', (e) => {
createTags(e.target.value)
if (e.key === 'Enter') {
setTimeout(() => {
e.target.value = ''
}, 10)
randomSelect()
}
})
function createTags(input) {
const tags = input.split(',').filter(tag => tag.trim() !==
'').map(tag => tag.trim())
tagsEl.innerHTML = ''
tags.forEach(tag => {
const tagEl = document.createElement('span')
tagEl.classList.add('tag')
tagEl.innerText = tag
tagsEl.appendChild(tagEl)
})
}
let selectInterval = null;
function randomSelect() {
const times = 30
// Is there an interval running? cancel it
if (selectInterval) window.clearInterval(selectInterval);
selectInterval = setInterval(() => {
const randomTag = pickRandomTag()
// Do we have something to toggle? If no, exit
if (!randomTag) return;
highlightTag(randomTag)
setTimeout(() => {
unHighlightTag(randomTag)
}, 1000)
}, 1000);
}
function pickRandomTag() {
const tags = document.querySelectorAll('.tag')
return tags[Math.floor(Math.random() * tags.length)]
}
function highlightTag(tag) {
tag?.classList?.add('hightlight')
}
function unHighlightTag(tag) {
tag?.classList?.remove('hightlight')
}
* {
box-sizing: border-box;
}
body {
background-color: #2b88f0;
font-family: 'Roboto', sans-serif;
display: flex;
flex-direction: column;
align-items: center;
justify-content: center;
height: 100vh;
overflow: hidden;
margin: 0;
}
h3 {
color: #fff;
margin: 10px 0 20px;
text-align: center;
}
.container {
width: 500px;
}
textarea {
border: none;
display: block;
width: 100%;
height: 100px;
font-family: inherit;
padding: 10px;
margin: 0 0 20px;
font-size: 16px;
}
.tag {
background-color: #f0932b;
color: #fff;
border-radius: 50px;
padding: 10px 20px;
margin: 0 5px 10px 0;
font-size: 14px;
display: inline-block;
}
.tag.hightlight {
background-color: #273c75;
}
<link href="https://fonts.googleapis.com/css2?family=Roboto&display=swap&ext=.css" rel="stylesheet" />
<div class="container">
<h3>Enter all of the choices divided by a comma (','). <br> Press Enter when you are done</h3>
<textarea placeholder="Enter choices here..." id="textarea"></textarea>
<div id="tags">
</div>
</div>
<script src="script.js"></script>

Buttons not working xxxxx.addEventListener is not a function

I created a 16 x 16 grid where I can etch a sketch on that grid. It's working with the default colour that I use. When I try adding buttons to change colours to sketch. I can't seem to make it work. I've tried various methods and writing it with various ways but again and again I failed. I want when I click on the buttons, it changes colour when I sketch. I'll include below the previous code that's working and one of the ways that I've tried. Any expert/master please have a look on my code.
let container = document.querySelector('.container');
let rows = document.getElementsByClassName('gridRow');
let columns = document.getElementsByClassName('gridColumn');
const blue = document.getElementsByClassName('blue');
const eraser = document.getElementsByClassName('eraser');
const black = document.getElementsByClassName('black');
let reset = document.getElementById('reset');
function createGrid(number) {
makeRow(number);
makeColumn(number);
changeColours();
}
function makeRow(numberOfRow) {
for (let i = 0; i <numberOfRow; i++) {
let row = document.createElement('div');
container.appendChild(row);
row.classList.add('gridRow');
}
}
function makeColumn(numberOfColumn, selection) {
for ( let i = 0; i < rows.length; i++) {
for ( let j = 0; j < numberOfColumn; j++) {
let column = document.createElement('div');
The part below is what I tried, erase it if you want it to work with just one colour
if (selection == 'blue') {
column.addEventListener('mouseenter', function() {
column.classList.add('blue');
})
} else if (selection == 'eraser') {
column.addEventListener('mouseenter', function() {
column.classList.add('eraser');
})
} else if (selection == 'black') {
column.addEventListener('mouseenter', function() {
column.classList.add('black');
})
} else {
column.addEventListener('mouseenter', function() {
column.classList.add('colored');
})
}
// column.addEventListener('mouseleave', () => {
// column.classList.remove('colored');
// })
Just erase part of the code above if you want to make it work
rows[j].appendChild(column);
column.classList.add('gridColumn');
}
}
}
The part below is what I tried, erase it if you want it to work with just one colour
blue.addEventListener('click', function() {
makeColumn(number, 'blue');
})
eraser.addEventListener('click', function() {
makeColumn(number, 'white');
})
black.addEventListener('click', function() {
makeColumn(number, 'black');
})
Just erase part of the code above if you want to make it work
createGrid(16);
#importurl('https://fonts.googleapis.com/css2family=Asap:wght#400;600;700&display=swap');
body {
display: flex;
height: 100%;
width: 100%;
flex-direction: column;
background-color: beige;
font-family: Asap, sans-serif;
margin: 0;
padding: 0;
justify-content: center;
align-content: center;
align-items: center;
}
.header {
display: flex;
flex: 1;
justify-content: center;
}
#setGridSize {
display: inline-flex;
justify-content: center;
flex: 1;
gap: 12px;
}
#guide {
text-align: center;
margin: 1px;
font-family: Asap, sans-serif;
color: red;
font-size: 13px;;
}
.container {
display: flex;
justify-content: center;
align-content: center;
align-items: center;
border: 1px solid black;
width: 550px;
height: 550px;
}
.gridColumn {
display: inline-flex;
border: 1px solid beige;
margin: -1px 0;
width: 30px;
height: 30px;
}
.colored{
background: red;
}
.buttons {
display: flex;
flex: 1;
gap: 20px;
margin: 10px;
}
.blue {
background: blue;
}
.eraser {
background: white;
}
.black {
background: black;
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>DOM Manipulation and Events</title>
<script src="javascript.js" defer></script>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<h1 class="header"> Let's sketch ! </h1>
<div id="setGridSize">
<p> Grid size </p> <input type="text" placeholder="Size of Board" class="size-box">
<button id="submit" > Submit </button>
</div>
<p id="guide"> Enter a number between 2 to 99</p>
<div class="container"></div>
<div class="buttons">
<button class="blue"> Blue </button>
<button class="eraser" > Eraser </button>
<button class="black"> Black </button>
<button class="rainbow" > Rainbow </button>
<button class="reset" > Reset</button>
</div>
</body>
</html>

Maybe this small example will help you
const grid = document.querySelector('.grid');
const colorSelector = document.querySelector('input[type="color"]')
const COUNT = 8
for (let i = 0; i < COUNT; i++) {
for (let j = 0; j < COUNT; j++) {
const btn = document.createElement('button')
grid.appendChild(btn)
}
}
const btns = Array.from(grid.children)
btns.forEach(btn => {
btn.addEventListener('mouseenter', event => {
btn.style.backgroundColor = colorSelector.value;
})
})
#import "https://cdn.jsdelivr.net/gh/KunalTanwar/normalize/css/normalize.inter.min.css";
body {
height: 100%;
display: grid;
place-items: center;
}
.grid {
--btn-count: 8;
--btn-size: 24px;
display: grid;
grid-template-columns: repeat(var(--btn-count), var(--btn-size));
grid-template-rows: repeat(var(--btn-count), var(--btn-size));
}
.grid button {
border: 1px solid #d1d1d1;
}
<input type="color">
<div class="grid"></div>

when adding a new item the functionality of the previous item changes

const addBtn = document.querySelector(".add");
const modal = document.querySelector(".modal__container");
const library = document.querySelector(".library__container");
const submitBook = document.querySelector(".add__book");
const deleteBtn = document.querySelector(".fas fa-trash-alt");
//Modal inputs
const modalTitle = document.querySelector("#title");
const modalAuthor = document.querySelector("#author");
const modalPages = document.querySelector("#pages");
const isRead = document.querySelector("#read-status");
//Toggle Modal
const hideModal = () => {
modal.style.display = "none";
};
const showModal = () => {
modal.style.display = "block";
const cancel = document.querySelector(".cancel");
cancel.addEventListener("click", (e) => {
e.preventDefault();
hideModal();
});
};
addBtn.addEventListener("click", showModal);
let myLibrary = [];
let index = 0;
function Book(title, author, pages, read) {
this.title = title,
this.author = author,
this.pages = pages,
this.read = read
}
submitBook.addEventListener("click", addBookToLibrary);
function addBookToLibrary(e) {
e.preventDefault();
let bookTitle = modalTitle.value;
let bookAuthor = modalAuthor.value;
let bookPages = modalPages.value;
let bookStatus = isRead.checked;
//Display error message if inputs are empty
if (bookTitle === "" || bookAuthor === "" || bookPages === "") {
const errorMessage = document.querySelector(".error__message--container");
hideModal();
errorMessage.style.display = "block";
const errorBtn = document.querySelector(".error-btn");
errorBtn.addEventListener("click", () => {
errorMessage.style.display = "none";
showModal();
})
} else {
let book = new Book(bookTitle, bookAuthor, bookPages, bookStatus);
myLibrary.push(book);
hideModal();
render();
}
}
function render() {
library.innerHTML = "";
for (let i = 0; i < myLibrary.length; i++) {
library.innerHTML +=
'<div class="book__container">' +
'<div class="book">' +
'<div class="title__content">' +
'<span class="main">Title : </span><span class="book__title">' +` ${myLibrary[i].title}`+'</span>' +
'</div>' +
'<div class="author__content">' +
'<span class="main">Author : </span><span class="book__author">'+` ${myLibrary[i].author}`+'</span>' +
'</div>' +
'<div class="pages__content">' +
'<span class="main">Pages : </span><span class="book__pages">'+` ${myLibrary[i].pages}`+'</span>' +
'</div>' +
'<div class="book__read-elements">' +
'<span class="book__read">I read it</span>' +
'<i class="fas fa-check"></i>' +
'<a href="#"><i class="fas fa-times"></i>' +
'<i class="fas fa-trash-alt"></i>' +
'</div>' +
'</div>' +
'</div>'
readStatus(myLibrary[i].checked)
}
modalTitle.value = "";
modalAuthor.value = "";
modalPages.value = "";
isRead.checked = false;
}
function readStatus(bookStatus) {
const bookStatusContainer = document.querySelector(".book__read");
if (bookStatus) {
bookStatusContainer.classList.add("yes");
bookStatusContainer.textContent = "I read it";
bookStatusContainer.style.color = "rgb(110, 176, 120)";
} else {
bookStatusContainer.classList.add("no");
bookStatusContainer.textContent = "I have not read it";
bookStatusContainer.style.color = "rgb(194, 89, 89)";
}
}
#import url('https://fonts.googleapis.com/css2?family=Poppins:wght#300;400;600&display=swap');
:root {
--light-gray: #dededef3;
--title-color: #333756;
--main-color: #c6c6c6f3;
}
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
body {
font-family: 'Poppins', sans-serif;
background-color: var(--light-gray);
}
header {
text-align: center;
padding-top: 4rem;
color: var(--title-color);
text-transform: uppercase;
letter-spacing: 4px;
}
button {
margin: 1rem;
padding: 0.8rem 2rem;
font-size: 14px;
border-radius: 25px;
background: white;
color: #333756;
font-weight: 600;
border: none;
cursor: pointer;
transition: 0.6s all ease;
}
:focus {
/*outline: 1px solid white;*/
}
button:hover {
background: var(--title-color);
color: white;
}
.add__book:hover,
.cancel:hover {
background: var(--main-color);
color: var(--title-color)
}
.all,
.books__read,
.books__not-read {
border-radius: 0;
text-transform: uppercase;
letter-spacing: 0.1rem;
background: var(--light-gray);
border-bottom: 4px solid var(--title-color)
}
.library__container {
display: flex;
justify-content: center;
flex-wrap: wrap;
}
.book__container {
display: flex;
margin: 2rem 2rem;
}
.modal__container {
display: none;
position: fixed;
z-index: 4;
top: 0;
left: 0;
width: 100%;
height: 100%;
background-color: rgba(0, 0, 0, 0.4);
padding-top: 0px;
}
.book,
.modal {
padding: 2rem 2rem;
border-radius: 15px;
background: #333756;
line-height: 3rem;
}
.modal {
position: relative;
width: 50%;
margin: 0 auto;
margin-top: 8rem;
}
.modal__content {
display: flex;
flex-direction: column;
}
label {
color: white;
margin-right: 1rem;
}
input {
padding: 0.5rem;
font-size: 14px;
}
.book__read-elements {
display: flex;
justify-content: space-between;
}
.main,
i {
color: white;
pointer-events: none;
margin: 0.5rem;
}
.book__title,
.book__author,
.book__pages,
.book__read {
color: var(--main-color)
}
.error__message--container {
display: none;
position: fixed;
z-index: 4;
top: 0;
left: 0;
width: 100%;
height: 100%;
background-color: rgba(0, 0, 0, 0.4);
}
.error__message--modal {
position: relative;
margin: 0 auto;
margin-top: 10rem;
width:40%;
}
.error {
display: flex;
flex-direction: column;
align-items: center;
color: rgb(101, 3, 3);
font-size: 20px;
font-weight: bold;
background: rgb(189, 96, 96);
padding: 3rem 5rem;
border-radius: 10px;
}
.error-btn {
color: rgb(101, 3, 3);
font-weight: bold;
}
.error-btn:hover {
color: white;
background: rgb(101, 3, 3);
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.13.1/css/all.min.css" integrity="sha256-2XFplPlrFClt0bIdPgpz8H7ojnk10H69xRqd9+uTShA=" crossorigin="anonymous" />
<link rel="stylesheet" href="styles.css">
<title>Library</title>
</head>
<body>
<header>
<h1>My Library</h1>
<button class="add">Add New Book</button>
<div class="buttons">
<button class="all">View All</button>
<button class="books__read">Read</button>
<button class="books__not-read">Not Read</button>
</div>
</header>
<div class="error__message--container">
<div class="error__message--modal">
<div class="error">
<p>Complete the form!</p>
<button class ="error-btn">Ok</button>
</div>
</div>
</div>
<!--Modal-->
<form class="modal__container">
<div class="modal">
<div class="modal__content">
<label for="">Title:</label>
<input type="text" id="title">
</div>
<div class="modal__content">
<label for="">Author:</label>
<input type="text" id="author">
</div>
<div class="modal__content">
<label for="">Pages:</label>
<input type="number" id="pages">
</div>
<div>
<label for="read-status">Check the box if you've read this book</label>
<input type="checkbox" id="read-status" value ="check">
</div>
<button class="add__book">Add</button>
<button class="cancel">Cancel</button>
</div>
</form>
<!--End of Modal-->
<div class="library__container"></div>
<script src="script.js"></script>
</body>
</html>
I'm new to OOP and I'm struggling.
I'm building a library where you can add a book with the title, author nr of pages and if you've read it or not. When I add the first book if I check the box it displays that to book is not read(which is false). When I add a new book the read functionality is not applied to that book at all. I have no idea how to fix it

In this function you are checking the status if isRead which is incorrect.
Do this
Call the readStatus function inside the for loop
Pass the current parameter readStatus(myLibrary[i].checked)
Modify readStatus as shown below
function readStatus(status) {
const bookReadStatus = document.querySelector(".book__read");
if (status) {
bookReadStatus.classList.add("yes");
bookReadStatus.textContent = "I read it";
bookReadStatus.style.color = "rgb(110, 176, 120)";
} else {
bookReadStatus.classList.add("no");
bookReadStatus.textContent = "I have not read it";
bookReadStatus.style.color = "rgb(194, 89, 89)";
}
}

Adding a square root function to a calc using js

So, I made a calculator, and I want to add a square root function, but I know there is no already made function that finds the square root of numbers. So what elements can I combine to find the square root of a number?
const screen = document.querySelector("#screen");
const clearButton = document.querySelector("#clear");
const equalsButton = document.querySelector("#equals");
const decimalButton = document.querySelector("#decimal");
let isFloat = false;
let signOn = false;
let firstNumber = "";
let operator = "";
let secondNumber = "";
let result = "";
const allClear = () => {
isFloat = false;
signOn = false;
firstNumber = "";
operator = "";
secondNumber = "";
result = "";
screen.value = "0";
};
const calculate = () => {
if (operator && result === "" && ![" ", "+", "-", "."].includes(screen.value[screen.value.length - 1])) {
secondNumber = screen.value.substring(firstNumber.length + 3);
switch (operator) {
case "+":
result = Number((Number(firstNumber) + Number(secondNumber)).toFixed(3));
break;
case "-":
result = Number((Number(firstNumber) - Number(secondNumber)).toFixed(3));
break;
case "*":
result = Number((Number(firstNumber) * Number(secondNumber)).toFixed(3));
break;
case "/":
result = Number((Number(firstNumber) / Number(secondNumber)).toFixed(3));
break;
default:
}
screen.value = result;
}
};
clear.addEventListener("click", allClear);
document.querySelectorAll(".number").forEach((numberButton) => {
numberButton.addEventListener("click", () => {
if (screen.value === "0") {
screen.value = numberButton.textContent;
} else if ([" 0", "+0", "-0"].includes(screen.value.substring(screen.value.length - 2))
&& numberButton.textContent === "0") {
} else if ([" 0", "+0", "-0"].includes(screen.value.substring(screen.value.length - 2))
&& numberButton.textContent !== "0") {
screen.value = screen.value.substring(0, screen.value.length - 1) + numberButton.textContent;
} else if (result || result === 0) {
allClear();
screen.value = numberButton.textContent;
} else {
screen.value += numberButton.textContent;
}
});
});
decimalButton.addEventListener("click", () => {
if (result || result === 0) {
allClear();
isFloat = true;
screen.value += ".";
} else if (!isFloat) {
isFloat = true;
if ([" ", "+", "-"].includes(screen.value[screen.value.length - 1])) {
screen.value += "0.";
} else {
screen.value += ".";
}
}
});
document.querySelectorAll(".operator").forEach((operatorButton) => {
operatorButton.addEventListener("click", () => {
if (result || result === 0) {
isFloat = false;
signOn = false;
firstNumber = String(result);
operator = operatorButton.dataset.operator;
result = "";
screen.value = `${firstNumber} ${operatorButton.textContent} `;
} else if (operator && ![" ", "+", "-", "."].includes(screen.value[screen.value.length - 1])) {
calculate();
isFloat = false;
signOn = false;
firstNumber = String(result);
operator = operatorButton.dataset.operator;
result = "";
screen.value = `${firstNumber} ${operatorButton.textContent} `;
} else if (!operator) {
isFloat = false;
firstNumber = screen.value;
operator = operatorButton.dataset.operator;
screen.value += ` ${operatorButton.textContent} `;
} else if (!signOn
&& !["*", "/"].includes(operatorButton.dataset.operator)
&& screen.value[screen.value.length - 1] === " ") {
signOn = true;
screen.value += operatorButton.textContent;
}
});
});
equalsButton.addEventListener("click", calculate);
* {
box-sizing: border-box;
font-family: 'Roboto', sans-serif;
font-weight: 300;
margin: 0;
padding: 0;
}
body {
background-color: #222;
height: 100vh;
}
header {
background-color: #333;
padding: 40px 0;
}
header h1 {
-webkit-background-clip: text;
background-clip: text;
background-image: linear-gradient(to right bottom, #fff, #777);
color: transparent;
font-size: 40px;
letter-spacing: 2px;
text-align: center;
text-transform: uppercase;
}
main {
background-color: #222;
display: flex;
justify-content: center;
padding: 60px 0;
}
main #container {
background-color: #333;
box-shadow: 0 5px 5px #111;
padding: 20px;
}
.clearfix:after {
clear: both;
content: " ";
display: block;
font-size: 0;
height: 0;
visibility: hidden;
}
#container .row:not(:last-child) {
margin-bottom: 9px;
}
#container input,
#container button {
float: left;
}
#container input:focus,
#container button:focus {
outline: none;
}
#container input {
background-color: #222;
border: 1px solid #999;
border-right-width: 0;
color: #999;
font-size: 22px;
font-weight: 300;
height: 80px;
padding-right: 14px;
text-align: right;
width: 261px;
}
#container button {
background-color: #222;
border: none;
box-shadow: 0 3px 0 #111;
color: #999;
font-size: 20px;
height: 80px;
margin-right: 7px;
width: 80px;
}
#container button:active {
box-shadow: 0 2px 0 #111;
transform: translateY(1px);
}
#container #clear,
#container .operator,
#container #equals {
color: #111;
}
#container #clear,
#container .operator {
margin-right: 0;
}
#container #clear {
background-color: #e95a4b;
border: 1px solid #999;
border-left-width: 0;
box-shadow: none;
cursor: pointer;
}
#container #clear:active {
box-shadow: none;
transform: none;
}
#container .operator {
background-color: #999;
box-shadow: 0 3px 0 #555;
}
#container .operator:active {
box-shadow: 0 2px 0 #555;
}
#container #equals {
background-color: #2ecc71;
box-shadow: 0 3px 0 #155d34;
}
#container #equals:active {
box-shadow: 0 2px 0 #155d34;
}
#media only screen and (max-width: 400px) {
header {
padding: 28px 0;
}
header h1 {
font-size: 36px;
}
main {
padding: 40px 0;
}
main #container {
padding: 16px;
}
#container .row:not(:last-child) {
margin-bottom: 7px;
}
#container input {
font-size: 18px;
height: 60px;
padding-right: 10px;
width: 195px;
}
#container button {
font-size: 16px;
height: 60px;
margin-right: 5px;
width: 60px;
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<title>Calculator</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link href="https://fonts.googleapis.com/css?family=Roboto:300" rel="stylesheet">
<link href="Project 1.css" rel="stylesheet">
</head>
<body>
<header>
<h1>Calculator</h1>
</header>
<main>
<div id="container">
<div class="row clearfix">
<input id="screen" value="0" disabled type="text">
<button id="clear">AC</button>
</div>
<div class="row clearfix">
<button class="number">1</button>
<button class="number">2</button>
<button class="number">3</button>
<button data-operator="+" class="operator">+</button>
</div>
<div class="row clearfix">
<button class="number">4</button>
<button class="number">5</button>
<button class="number">6</button>
<button data-operator="-" class="operator">-</button>
</div>
<div class="row clearfix">
<button class="number">7</button>
<button class="number">8</button>
<button class="number">9</button>
<button data-operator="*" class="operator">×</button>
</div>
<div class="row clearfix">
<button id="decimal">.</button>
<button class="number">0</button>
<button id="equals">=</button>
<button data-operator="/" class="operator">÷</button>
</div>
</div>
</main>
<script src="Project 1.js"></script>
</body>
</html>
This is the code for the calc.. Feel free to edit it and explain to me what you did.

There is already one.
The Math.sqrt() function returns the square root of a number, that is, ∀x≥0,Math.sqrt(x)=x
=the uniquey≥0such thaty2=x
MDN Docs

You can use javascript built in
Math.sqrt(number)

jQuery - whenever reset is clicked it does not reset blocks

The reset button makes the grid disappear.
There are two functions that are causing this problem:
reset()
main()
The reason why the grid is disappearing is because of the .empty() method that is attached to the containerGrid and that is inside the main function and because of the $resetButton.on("click", reset), the reset parameter should have () with an argument passed in.
Here is what I tried:
$resetButton.on("click", reset());
This helps with not deleting the grid, but it does not erase the color or gradient blocks anymore.
/*---------------------------
Variables
---------------------------*/
const $containerGrid = $(".containerGrid");
let boxSide = 16;
const $gridLength = $("#gridLength");
const $gradientButton = $("#gradient");
const $randomButton = $("#random");
const $resetButton = $("#reset");
/*-- -------------------------
Buttons & input
---------------------------*/
$gridLength.on("input", gridLength);
$gradientButton.on("click", incrementOpacity);
$randomButton.on("click", getRandomColors);
$resetButton.on("click", reset(16));
/*---------------------------
Corresponding to Event listeners
---------------------------*/
function gridLength() {
if (event.target.value !== 16) {
reset(event.target.value);
}
}
function incrementOpacity() {
$(".cell").off("mouseenter");
$(".cell").mouseenter((event) => {
let opacity = parseFloat(event.target.style.opacity);
if (opacity <= 0.9) {
$(event.target).css({
"opacity": `${opacity + 0.1}`,
"backgroundColor": "#f5f5f5"
});
}
});
}
function setRandomColors() {
return Math.floor((Math.random() * 256));
}
function getRandomColors() {
$(".cell").off("mouseenter");
$(".cell").mouseenter((event) => {
$(event.target).css({
"backgroundColor": `rgb(${setRandomColors()}, ${setRandomColors()}, ${setRandomColors()})`,
"opacity": "1"
})
});
}
function reset(length) {
boxSide = length;
main();
$(".cell").css({
"opacity": "0.1",
"border": "0.5px solid black",
"backgroundColor": "transparent"
});
}
/*-- -------------------------
Creates the Grid
------------------------------*/
function main() {
$($containerGrid).empty();
for (let row = 0; row < boxSide; row++) {
for (let column = 0; column < boxSide; column++) {
createCell();
}
}
$(".cell").css("height", `${(300 / boxSide) - 1}px`);
$(".cell").css("width", `${(300 / boxSide) - 1}px`);
}
function createCell() {
const $cell = $('<div class="cell"></div>');
$cell.css("opacity", "0.1");
$containerGrid.append($cell);
}
main();
* {
margin: 0;
padding: 0;
outline: 0;
font-family: Arial, Helvetica, sans-serif;
color: var(--font-color);
}
:root {
--linear-color1: #e66465;
--linear-color2: #9198e5;
--font-color: #ffffff;
--black-color: #000000;
}
body,
html {
background: linear-gradient(190deg, var(--linear-color1), var(--linear-color2));
height: 100vh;
}
.container {
display: flex;
flex-direction: column;
align-items: center;
}
.title header h1 {
margin: 1em 0em 1em 0;
}
.containerGrid {
display: flex;
flex-wrap: wrap;
width: 300px;
height: 300px;
margin-bottom: 3em;
}
.cell {
height: 15px;
width: 15px;
border-radius: 3px;
border: 0.5px solid var(--black-color);
}
.options {
display: flex;
justify-content: space-around;
}
button,
input {
background-color: transparent;
padding: .5em;
border: 1px solid var(--font-color);
border-radius: 3px;
transition: 1s all ease;
}
button:hover,
input:hover {
background-color: var(--font-color);
color: var(--black-color);
}
button:focus,
input:focus {
background-color: var(--font-color);
color: var(--black-color);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<!-- ------------------------- How to Play --------------------------->
<div class="container">
<div class="title">
<header>
<h1>Etch a Sketch</h1>
</header>
</div>
<!-- ------------------------- Grid --------------------------->
<section>
<div class="containerGrid">
</div>
<div class="options">
<input type="number" id="gridLength" value="16" min="3" max="64">
<button type="submit" id="gradient">Gradient</button>
<button type="submit" id="random">Random</button>
<button type="reset" id="reset">Reset</button>
</div>
</section>
</div>
Expected: to just erase the the colorful and gradient blocks and the leave the grid size alone
Actual result: The grid does not disappear but it will not erase the colored and gradients blocks anymore. It should just reset everything except for the grid size

You set click event to your reset button the wrong way. The below code should work:
$resetButton.on("click", function() {
reset(16);
});
Full code:
/*---------------------------
Variables
---------------------------*/
const $containerGrid = $(".containerGrid");
let boxSide = 16;
const $gridLength = $("#gridLength");
const $gradientButton = $("#gradient");
const $randomButton = $("#random");
const $resetButton = $("#reset");
/*-- -------------------------
Buttons & input
---------------------------*/
$gridLength.on("input", gridLength);
$gradientButton.on("click", incrementOpacity);
$randomButton.on("click", getRandomColors);
$resetButton.on("click", function() {
reset(16);
});
/*---------------------------
Corresponding to Event listeners
---------------------------*/
function gridLength() {
if (event.target.value !== 16) {
reset(event.target.value);
}
}
function incrementOpacity() {
$(".cell").off("mouseenter");
$(".cell").mouseenter((event) => {
let opacity = parseFloat(event.target.style.opacity);
if (opacity <= 0.9) {
$(event.target).css({
"opacity": `${opacity + 0.1}`,
"backgroundColor": "#f5f5f5"
});
}
});
}
function setRandomColors() {
return Math.floor((Math.random() * 256));
}
function getRandomColors() {
$(".cell").off("mouseenter");
$(".cell").mouseenter((event) => {
$(event.target).css({
"backgroundColor": `rgb(${setRandomColors()}, ${setRandomColors()}, ${setRandomColors()})`,
"opacity": "1"
})
});
}
function reset(length) {
boxSide = length;
main();
$(".cell").css({
"opacity": "0.1",
"border": "0.5px solid black",
"backgroundColor": "transparent"
});
}
/*-- -------------------------
Creates the Grid
------------------------------*/
function main() {
$($containerGrid).empty();
for (let row = 0; row < boxSide; row++) {
for (let column = 0; column < boxSide; column++) {
createCell();
}
}
$(".cell").css("height", `${(300 / boxSide) - 1}px`);
$(".cell").css("width", `${(300 / boxSide) - 1}px`);
}
function createCell() {
const $cell = $('<div class="cell"></div>');
$cell.css("opacity", "0.1");
$containerGrid.append($cell);
}
main();
* {
margin: 0;
padding: 0;
outline: 0;
font-family: Arial, Helvetica, sans-serif;
color: var(--font-color);
}
:root {
--linear-color1: #e66465;
--linear-color2: #9198e5;
--font-color: #ffffff;
--black-color: #000000;
}
body,
html {
background: linear-gradient(190deg, var(--linear-color1), var(--linear-color2));
height: 100vh;
}
.container {
display: flex;
flex-direction: column;
align-items: center;
}
.title header h1 {
margin: 1em 0em 1em 0;
}
.containerGrid {
display: flex;
flex-wrap: wrap;
width: 300px;
height: 300px;
margin-bottom: 3em;
}
.cell {
height: 15px;
width: 15px;
border-radius: 3px;
border: 0.5px solid var(--black-color);
}
.options {
display: flex;
justify-content: space-around;
}
button,
input {
background-color: transparent;
padding: .5em;
border: 1px solid var(--font-color);
border-radius: 3px;
transition: 1s all ease;
}
button:hover,
input:hover {
background-color: var(--font-color);
color: var(--black-color);
}
button:focus,
input:focus {
background-color: var(--font-color);
color: var(--black-color);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<!-- ------------------------- How to Play --------------------------->
<div class="container">
<div class="title">
<header>
<h1>Etch a Sketch</h1>
</header>
</div>
<!-- ------------------------- Grid --------------------------->
<section>
<div class="containerGrid">
</div>
<div class="options">
<input type="number" id="gridLength" value="16" min="3" max="64">
<button type="submit" id="gradient">Gradient</button>
<button type="submit" id="random">Random</button>
<button type="reset" id="reset">Reset</button>
</div>
</section>
</div>