I have written JavaScript function, to shuffle an array of divs onClick.
// Function to shuffle 3 divs
shuffle = () => {
const shuffled = this.state.divs.sort(() => Math.random() - .50);
this.setState([...shuffled]);
};
// Button as an FYI
<button onClick={this.shuffle} className="has-text-black">shuffle hats</button>
This works absolutely fine, and randomises every time I click the button.
However, I want the divs to sort/shuffle 5 times automatically, onClick.
(IE = I don't want to have to click 5 times, to shuffle 5 times).
What's the best approach to do this?
(I've searched but haven't found anything to repeat shuffling on elements).
I thought about using async await/settimeout, to repeat this.state.divs.sort(() => Math.random() - .50) 5 times?
UPDATE:
To add context, here is a codesandbox...
https://codesandbox.io/s/distracted-shape-ifsiv
When I click the shuffle button, you can see the hats only swap positions once. Not 5 times.
Here is a posible way to do it, with javascript.
hats object get shuffled 5 times, with 200ms second transition.
Of course it's very simple, the object is meant to be extended!
let hats = [
{content: `<h6>1🎩</h6>`},
{content: `<h3>2🎩</h3>`},
{content: `<h1>3🎩</h1>`},
{content: `<h2>4🎩</h2>`},
{content: `<h4>5🎩</h4>`}
];
let timer;
function loop5(){
let i = 0
clearInterval(timer)
timer = setInterval(function(){
shuffle()
if (i >= 5){
clearInterval(timer)
}
i++
}, 200)
}
function shuffle(){
hats.sort(() => Math.random() - 0.5)
out.innerHTML = hats.map(e => e.content).join("")
}
div {display: flex; font-size: xx-large }
<button onclick="loop5()">shuffle hats</button>
<div id="out"></div>
I don't see why shuffling 5 times is better or any different than shuffling 5 times. Anyway you can do it in a naive way like this:
// Function to shuffle 3 divs
shuffle = () => {
const shuffled = this.state.divs.sort(() => Math.random() - .50);
this.setState([...shuffled]);
};
shuffleTimesFive = () => {
for(var i = 0; i < 5; i++)
this.shuffle();
}
// Button as an FYI
<button onClick={this.shuffleTimesFive} className="has-text-black">shuffle hats</button>
Or maybe a smarter way is to have a shuffleNTimes function that takes a parameter, like so:
// Function to shuffle 3 divs
shuffle = () => {
const shuffled = this.state.divs.sort(() => Math.random() - .50);
this.setState([...shuffled]);
};
shuffleNTimes = (n) => {
for(var i = 0; i < n; i++)
this.shuffle();
}
// Button as an FYI
<button onClick={this.shuffleNTimes.bind(this, 5)} className="has-text-black">shuffle hats</button>
I think shuffling one time and five times has the same effect, and Fisher-Yates is more efficient but keeping your way:
shuffle = () => {
let shuffled = [];
for(let i=0; i<5; i++)
shuffled = this.state.divs.sort(() => Math.random() - .50);
this.setState([...shuffled]);
};
If you decide to use "Fisher-Yates" algorithm, you can implement it like:
const shuffle = () => {
let array = this.state.divs;
for (let i = array.length - 1; i > 0; i--) {
const j = Math.floor(Math.random() * (i + 1));
[array[i], array[j]] = [array[j], array[i]];
}
this.setState([...array]);
}
As I understood from your comment, you want to do animation, in this case you don't need a loop rather you can use setInterval() and reset it ones executed five times. I have written a demo on both shuffling ways, as you can see the method that uses sort() sometimes returns the same result while the "Fisher–Yates" always reshuffled.
<button onclick="shuffle()">Click To Shuffle</button>
<div id="1">div1</div>
<div id="2">div2</div>
<div id="3">div3</div>
<div id="4">div4</div>
<script>
//This one uses Fisher–Yates shuffle algorithm:
const divs = [...document.querySelectorAll('div')];
const shuffle = () => {
let count = 0;
const intervalId = setInterval( function() {
for (let i = divs.length - 1; i > 0; i--) {
const j = Math.floor(Math.random() * (i + 1));
[divs[i], divs[j]] = [divs[j], divs[i]];
}
divs.forEach( div => document.body.appendChild(div) );
count++;
if(count === 5)
clearInterval(intervalId);
} ,1000)
}
</script>
<button onclick="shuffle()">Click To Shuffle</button>
<div id="1">div1</div>
<div id="2">div2</div>
<div id="3">div3</div>
<div id="4">div4</div>
<script>
const divs = [...document.querySelectorAll('div')];
shuffle = () => {
let shuffled = [];
let count = 0;
const intervalId = setInterval( function() {
shuffled = divs.sort(() => Math.random() - .50);
shuffled.forEach( div => document.body.appendChild(div) );
count++;
if(count === 5)
clearInterval(intervalId);
}, 1000 )
};
</script>
For your case, it would be like:
let divs = this.state.divs;
const shuffle = () => {
let count = 0;
const intervalId = setInterval( function() {
for (let i = divs.length - 1; i > 0; i--) {
const j = Math.floor(Math.random() * (i + 1));
[divs[i], divs[j]] = [divs[j], divs[i]];
}
this.setState([...divs]);
count++;
if(count === 5)
clearInterval(intervalId);
} ,1000)
}
Related
I'm sorry if there has already been such question, I haven't found.
I wanna make a progress (loading) animation with JS:
<div class = "load">
<div id = "load_fill"></div>
<p id = "percent">0%</p>
</div>
<script>
let percent = document.getElementById("percent");
let load_fill = document.getElementById("load_fill")
let j = 0;
let fill = () => {
j++;
percent.textContent = `${j}%`;
load_fill.style.width = `${j}%`
}
for (let i = 0; i < 100; i++){
setTimeout(fill, 200);
}
</script>
The problem is that the first iteration works with delay but others no;
Is there any way to make delay between each iteration?
Will be thankful for any answer.
new Array(100).map((el, ind) => ind).forEach((cur) => setTimeout(fill, (cur + 1) * 200))
Here, we space out each setTimeout by first creating a range array (the first part) before setting a time out 200 ms between each one.
I have an issue where I have an array containing a deck of cards (['A', 2,3,...'J',...])
I want to be able to pick a number of random cards and then get the total sum of them. for example J,4 should give me the total value of 14.
my current problem is that I can't figure out how to change the strings in the array to a number and
then add those together to get the total sum.
my current code is:
blackjackGame={
'you': 0,
'cards': ['A','2','3','4','5','6','7','8','9','10','J','Q','K'],
'cardsMap' : {'A':1, '2':2, '3':3, '4':4, '5':5, '6':6, '7':7, '8':8, '9':9, '10':10, 'J':10, 'Q':10, 'K':10},
}
let playerCards = 2
let card = [];
const YOU = blackjackGame['you']
// gives me a random card
function randomCard (){
let rand = Math.floor(Math.random()* 13)
return blackjackGame['cards'][rand];
}
// gives me the two starting cards for the player in an array so I can later add more
function start(){
for(let i= 0; i < playerCards; i++){
card.push(randomCard())
}
return card
}
function totalValue (player){
// this is where i have no idea what to do
// let player = card.reduce(function (a,b){
// return a +b
// }, 0)
// return player += blackjackGame['cardsMap'][card[0]]
}
console.log(start())
console.log(showScore(YOU)) ```
PS. I'm trying to create a blackjack game.
Your reduce code is fine. Just add the reference to blackjackGame.cardsMap to retrieve the value that corresponds to card b.
let sum = card.reduce(function(a, b) {
return a + blackjackGame.cardsMap[b];
}, 0);
Note that you cannot return that value via the argument of the function. Instead let the function return it with a return statement:
return sum;
const blackjackGame={
'you': 0,
'cards': ['A','2','3','4','5','6','7','8','9','10','J','Q','K']
}
let playerCards = 2
let card = [];
const YOU = blackjackGame['you']
function getCardValue(card) {
const v = blackjackGame['cards']
if(v.indexOf(card) === -1){
throw Error("not found")
}
// for each card above index 9 (10), always return 10
return v.indexOf(card) > 9 ? 10 : v.indexOf(card) + 1
}
function randomCard (){
let rand = Math.floor(Math.random()* 13)
return blackjackGame['cards'][rand];
}
function deal(){
for(let i= 0; i < playerCards; i++){
card.push(randomCard())
}
return card
}
function calculateValue (cards){
return cards.reduce(function (total, num){
return total + getCardValue(num)
}, 0)
}
document.getElementById('deal').addEventListener('click',(e) => {
const cards = deal()
console.log(cards)
const playerValue = calculateValue(cards)
YOU = playerValue
console.log(playerValue)
})
<html>
<head>
</head>
<body>
<button id="deal">Deal</button>
<span id=cards />
<span id=total />
</body>
</html>
You need a way to map the face to the value. This will work:
function getValueOfCard( face ) {
var cardOrder =" A234567891JQK";
var faceStart = (""+face).substring(0,1);
return Math.min(10, cardOrder.indexOf(faceStart))
}
If you want to get the values of all your cards, simply iterate over them (faster than reduce, and more easy to read).
Your card only needs the face and color, the other values follow.
card = { color: "spades", face : "King" };
getValueOfCard( card.face );
function totalValue ( playerHand ){
// assuming an array of cards is the player hand
var total = 0;
for ( var card in playerHand ) {
total += getValueOfCard( card.face );
}
return total;
}
I also recommend, that you create all your cards in one go, and then shuffle them, by picking two random numbers and switching these two cards. Do this in a loop for a couple of times, and you have a randomized stack of cards, which means you can actually treat it as a stack.
cardColors = ["♠","♥","♦","♣"];
cardFaces = ['A','2','3','4','5','6','7','8','9','10','J','Q','K'];
// create deck of cards
var stackOfCards = [];
for ( var a = 0; a < cardColors.length; a++ ) {
var curColor = cardColors[a];
for ( var i = 0; i < cardFaces.length; i++) {
var curFace = cardFaces[i];
card = { color : curColor, face : curFace };
stackOfCards.push(card);
}
}
// shuffle the deck
// then you can pop cards from the stack to deal...
function start () {
for (let i = 0; i < playerCards; i++) {
cards.push(randomCard())
}
totalValue(cards)
}
function totalValue (cards) {
cards.forEach((card) => {
blackjackGame.you += blackjackGame.cardsMap[card]
})
}
start()
console.log(blackjackGame.you)
You were on the right track with having a map. You can access objects with a variable by using someObj[yourVar]
I'm coding a sorting visualizer in ReactJS, and I use a state to hold the delay between each render.
When I change the slider of the delay, the sorting does not update.
I made it log the updated value, and in each loop I made it log the value it reads.
for some reason, when I read the getDelay inside the loop, and outside of it, they are different.
Here is the code:
import React, { useState, useEffect } from "react";
import "./SortingVisualizer.css";
class Bar {
constructor(value, className) {
this.value = value;
this.className = className;
}
}
const SortingVisualizer = () => {
const [getArray, setArray] = useState([Bar]); //array to hold the bars
const [getSlider, setSlider] = useState(50);
const [getDelay, setDelay] = useState(2);
//reset the array at the start
useEffect(() => {
resetArray(10);
}, []);
//function to reset the array
const resetArray = () => {
const array = [];
for (let i = 0; i < getSlider; i++) {
array.push(new Bar(randomInt(20, 800), "array-bar"));
}
setArray(array);
};
//a delay function. use like this: `await timer(time to wait)`
const timer = delay => {
return new Promise(resolve => setTimeout(resolve, delay));
};
//function to do buuble sort with given delay between each comparison
const bubbleSort = async () => {
let temp,
array = Object.assign([], getArray); // defining a temporary variable, and a duplicate array the the bars array
//looping from the array size to zero, in cycles
for (let i = array.length; i > 0; i--) {
//looping from the start of the section from the first loop to the end of it.
for (let j = 0; j < i - 1; j++) {
//changing the colors of the compared bares
array[j].className = "array-bar compared-bar";
array[j + 1].className = "array-bar compared-bar";
if (getDelay > 0) await timer(getDelay / 2);
setArray([...array]);
//comparing and switching if needed
if (array[j].value > array[j + 1].value) {
temp = array[j].value;
array[j].value = array[j + 1].value;
array[j + 1].value = temp;
setArray([...array]);
}
//updating the array and moving to the next pair
if (getDelay > 0) await timer(getDelay / 2);
array[j].className = "array-bar";
array[j + 1].className = "array-bar";
// Wait delay amount in ms before continuing, give browser time to render last update
}
array[i - 1].className = "array-bar completed-bar";
}
setArray([...array]);
console.log("done.");
};
const combSort = async () => {
let temp,
swapped,
array = Object.assign([], getArray); // defining a temporary variable, and a duplicate array the the bars array
//looping from the array size to zero, in cycles
for (let i = array.length; i > 0; i = Math.floor(i / 1.3)) {
//looping from the start of the section from the first loop to the end of it.
swapped = false;
for (let j = 0; j < array.length - i; j++) {
//changing the colors of the compared bares
array[j].className = "array-bar compared-bar";
array[j + i].className = "array-bar compared-bar";
setArray([...array]);
await timer(getDelay / 2);
//comparing and switching if needed
if (array[j].value > array[j + i].value) {
temp = array[j].value;
array[j].value = array[j + i].value;
array[j + i].value = temp;
setArray([...array]);
swapped = true;
await timer(getDelay / 2);
}
//updating the array and moving to the next pair
array[j].className = "array-bar";
array[j + i].className = "array-bar";
// Wait delay amount in ms before continuing, give browser time to render last update
console.log(getDelay);
}
//array[i - 1].className = "array-bar completed-bar";
if (i === 1 && swapped) i = 2;
}
setArray([...array]);
};
const sliderUpdate = e => {
setSlider(e.target.value);
resetArray(getSlider);
};
const delayUpdate = e => {
setDelay(e.target.value * 1);
console.log(getDelay);
};
return (
<>
<div className="menu">
<button onClick={() => resetArray()}>Geneate new array</button>
<button onClick={() => bubbleSort()}>Do bubble sort</button>
<button onClick={() => combSort()}>Do comb sort</button>
</div>
<div class="slide-container">
<input
type="range"
min="3"
max="250"
value={getSlider}
class="slider"
id="sizeSlider"
onChange={sliderUpdate}
/>
<input
type="range"
min="0"
max="1000"
value={getDelay}
class="slider"
id="delaySlider"
onChange={delayUpdate}
/>
</div>
<div className="array-container">
{getArray.map((bar, i) => (
<div
className={getArray[i].className}
key={i}
style={{ height: `${bar.value * 0.1}vh` }}
></div>
))}
</div>
</>
);
};
function randomInt(min, max) {
return Math.floor(Math.random() * (max - min + 1)) + min;
}
export default SortingVisualizer;
I don't know what the best solution is, but a solution would be to use useRef.
The problem is related to Why am I seeing stale props or state inside my function? : On each render you are creating new functions for bubbleSort and combSort. Those functions use the value of getDelay that existed at the moment those functions have been created. When one of the buttons is clicked the "version" of the function of the last render will be executed, so the value of getDelay that existed then and there will be used.
Now, changing the slider will cause a rerender, and thus new versions of bubbleSort and combSort are created ... but those are not the versions that are currently running!
useRef solves that problem because instead of directly referring to the delay, we are referring to an object whose current property stores the delay. The object doesn't change, but the current property does and every time it's accessed we get the current value. I highly encourage you to read the documentation.
After your state variables, add
const delayRef = useRef(getDelay);
delayRef.current = getDelay
The second line keeps the ref in sync with the state.
Everywhere else where you reference getDelay, except value of the slider itself, use delayRef.current instead. For example:
if (delayRef.current > 0) await timer(delayRef.current / 2);
Demo (couldn't get it to work on SO): https://jsfiddle.net/wuf496on/
I want to be able to click on the button below and shuffle the cards in my card deck.
So far I have created an event listener which when clicked calls the function shuffleCards which takes an array. The array I have passed in is the one provided to me in the exercise which is an array of cards.
Nothing happens when I click on the button, I know it is something to do with scope but I do not know how to amend my code to make this work properly.
Thank you in advance.
HTML
<button type="button" id="shuffle" class="shuffle" class="btn btn-lg btn-secondary">Shuffle</button>
JAVASCRIPT
// Part given in exercise which creates a deck of cards:
const suit = 'hearts';
const cardsWrapper = document.querySelector('.cards-wrapper');
function createCards() {
const cards = [];
// Create an array with objects containing the value and the suit of each card
for (let i = 1; i <= 13; i += 1) {
const cardObject = {
value: i,
suit,
};
cards.push(cardObject);
}
// For each dataObject, create a new card and append it to the DOM
cards.forEach((card, i) => {
const positionFromLeft = i * 15;
const cardElement = document.createElement('div');
cardElement.setAttribute('data-value', card.value);
cardElement.classList.add('card', `${card.suit}-${card.value}`);
cardElement.style.left = `${positionFromLeft}px`;
cardsWrapper.append(cardElement);
});
}
// part written by me
const shufflebtn = document.getElementById('shuffle');
shufflebtn.addEventListener("click", () => {
shuffleCards(cards);
})
function shuffleCards(array) {
var i = 0
, j = 0
, temp = null
for (i = array.length - 1; i > 0; i -= 1) {
j = Math.floor(Math.random() * (i + 1))
temp = array[i]
array[i] = array[j]
array[j] = temp
}
return array
}
made some changes to code where i am not talking about html instead giving a solution for your card shuffle.
created a create cards button which triggers createCards function then, try clicking your shuffle and see console log you can see a shuffled array.
Note: click on create cards Button before you click on shuffle as you might log empty array
Also i changed the scope of cards as it should be accessible to other functions
const suit = 'hearts';
var cards = [];
function createCards() {
for (let i = 1; i <= 13; i += 1) {
const cardObject = {
value: i,
suit,
};
cards.push(cardObject);
}
}
const shufflebtn = document.getElementById('shuffle');
const creatorBtn = document.getElementById('creator');
shufflebtn.addEventListener("click", () => {
cards = shuffleCards(cards);
})
creatorBtn.addEventListener("click", () => {
createCards();
})
function shuffleCards(array) {
var i = 0,
j = 0,
temp = null
for (i = array.length - 1; i > 0; i -= 1) {
j = Math.floor(Math.random() * (i + 1))
temp = array[i]
array[i] = array[j]
array[j] = temp
}
console.log(array)
return array;
}
<button type="button" id="shuffle" class="shuffle" class="btn btn-lg btn-secondary">Shuffle</button>
<button type="button" id="creator" class="creator" class="btn btn-lg btn-secondary">create cards</button>
I have array with 10 items, I calls one random item using a random number from 1 to 10, what to use to make a random number from 1 to 10, which will not happen again, and when all 10 is used, the program stops randomly? code
const num = () => Math.floor(Math.random() * 10);
const postWord = () => {
randomWord = word.innerText = words[num()].PL;
}
postWord();
submit.addEventListener("click", function() {
postWord();
});
Have you ever considered to move the array items?
var range = 10; // global variable
const num = () => Math.floor(Math.random() * range);
const postWord = () => {
randomWord = word.innerText = words[num()].PL;
for (var i=num(); i < range; i++) {
var temp = words[i];
words[i] = words[i+1];
words[i+1] = temp;
}
range--;
}
postWord();
submit.addEventListener("click", function() {
if (range) {
postWord();
}
});
I am not that familiar with JS but I guess my code can at least demonstrate my point.