How to use the mouseover and mouseout events to change background color of all of the generated divs/grid-items - Jquery

thelinuxlobster
April 10, 2023
232 views
3 votes
3 Answers

I am completing the "etch-a-sketch" challenge as part of TOP curriculum. I have successfully created a 16 x 16 grid utilizing JS DOM manipulation and CSS grid. The second part of my problem is to make each individual grid-item/cell change background color on hover. I chose to use JS with the mouseover Eventlistener, but also saw the CSS: hover Selector as a viable option when googling for information.

I have created 2 functions overing and outing to change the background color of the grid-item on hover using the "mouseover" event listener. The functions only work on the first generated cell/grid-item. May someone please explain how I can get my overing and outing functions to work on all grid-items.only 1st grid-item working

//Function and call to generate 16x16 grid of divs. 
document.getElementById("container");

function makeGrid(rows, cols) {
  container.style.setProperty('--grid-rows', rows)
  container.style.setProperty('--grid-cols', cols)
  for (c = 0; c < (rows * cols); c++) {
    let cell = document.createElement("div");
    cell.innerText = (c + 1);
    container.appendChild(cell).className = "grid-item";
  };
};
makeGrid(16, 16);
//Function to change background color of individual "grid-item" on hover.
document.querySelector('.grid-item').addEventListener('mouseover', overing);
document.querySelector('.grid-item').addEventListener('mouseout', outing);

function overing(ev) {
  ev.currentTarget.style.backgroundColor = 'red';
  console.log('mouseenter div');
}

function outing(ev) {
  ev.currentTarget.style.backgroundColor = 'white';
  console.log('mouseleave div');
}

:root {
  --grid-cols: 1;
  --grid-rows: 1;
}

#container {
  display: grid;
  grid-gap: 1em;
  grid-template-columns: repeat(var(--grid-cols), 1fr);
  grid-template-rows: repeat(var(--grid-rows), 1fr);
}

.grid-item {
  padding: 1em;
  border: 1px solid black;
  text-align: center;
}

<!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>Sketch-Book</title>
  <link rel="stylesheet" type="text/css" href="etchStyles.css" />
</head>

<body>
  <div id="container">
  </div>
</body>
<script type="text/javascript" src="etchScript.js"></script>

</html>

Answers

@Titus is right. But since you are using javascript to create each DOM node, you can exploit this fact to attach event listeners at creation time. Ex:

const overing = (ev) => {
  ev.currentTarget.style.backgroundColor = 'red';
  //console.log('mouseenter div');
};

const outing = (ev) => {
  ev.currentTarget.style.backgroundColor = 'white';
  //console.log('mouseleave div');
}

const makeGrid = (rows, cols) => {
  container.style.setProperty('--grid-rows', rows)
  container.style.setProperty('--grid-cols', cols)
  for (c = 0; c < (rows * cols); c++) {
    let cell = document.createElement("div");
    cell.innerText = (c + 1);
    cell.classList.add('grid-item');
    
    //  attach listeners here since you have a reference to the DOM node
    cell.addEventListener("mouseover", overing);
    cell.addEventListener("mouseout", outing);
    
    container.appendChild(cell);
  };
};

makeGrid(16, 16);

section {
  --grid-cols: 1;
  --grid-rows: 1;
}

#container {
  display: grid;
  grid-gap: 1em;
  grid-template-columns: repeat(var(--grid-cols), 1fr);
  grid-template-rows: repeat(var(--grid-rows), 1fr);
  
}

.grid-item {
  padding: 1em;
  border: 1px solid black;
  text-align: center;
}

.grid-item:hover {
  cursor: pointer;
}

<section>
    <div id="container">
    </div>
</section>

You could use css :hover, here is an example with a 3×3 grid:

.grid {
  display: grid;
  grid-template: repeat(3, 30vh) / repeat(3, 30vw);
  background-color: white;
  height: 94vh;
  width: 94vw;
  grid-row-gap:1vh;
  grid-column-gap:1vw;
}

.grid_element {
  display: flex;
  height: 100%;
  width: 100%;
  background-color: gray;
}

.grid_element:hover {
  background-color: red;
}

<div class="grid">
  <div class="grid_element"></div>
  <div class="grid_element"></div>
  <div class="grid_element"></div>
  <div class="grid_element"></div>
  <div class="grid_element"></div>
  <div class="grid_element"></div>
  <div class="grid_element"></div>
  <div class="grid_element"></div>
  <div class="grid_element"></div>
</div>

All modern browsers support template ref: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/template so lets’ use that instead of manually creating an element so out code can be smaller – especially if you add more content to each "cell" such as a set of spans, divs etc.

You can determine what you want for event handlers but you can add those right in the same loop when creating them.

NOTE: Probably want to create a new DIV just to append all the NEW items to before hitting the DOM and appending them all at once but I will leave that exercise to you as outside the question scope.

function makeGrid(rows, cols) {
  const container = document.getElementById("container");
  const template = document.getElementById("grid-cell-template");
  for (let c = 0; c < (rows * cols); c++) {
    const cloneCell = template.content.cloneNode(true);
    const newItem = cloneCell.querySelector(".grid-item");
    newItem.textContent = (c + 1);
    newItem.addEventListener('mouseenter', mouseEnterEventHandler);
    newItem.addEventListener('mouseleave', mouseLeaveEventHandler);
    newItem.addEventListener('mouseover', mouseOverEventHandler);
    container.appendChild(newItem);
  }
}
makeGrid(16, 16);

function mouseEnterEventHandler(event) {
  event.currentTarget.style.backgroundColor = '#FF000022';
}

function mouseLeaveEventHandler(event) {
  event.currentTarget.style.backgroundColor = '#FFFFFF';
  event.target.style.borderColor = "#000000";
}

function mouseOverEventHandler(event) {
  event.target.style.borderColor = "#00FF00";
}

body {
  font-size: 16px;
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --grid-cols: 16;
  --grid-rows: 16;
}

#container {
  display: grid;
  grid-gap: 0.5em;
  grid-template-columns: repeat(var(--grid-cols), 1fr);
  grid-template-rows: repeat(var(--grid-rows), 1fr);
}

.grid-item {
  padding: 1em;
  border: 1px solid #000000;
  text-align: center;
}

<body>
  <div id="container">
  </div>
  <template id="grid-cell-template">
  <div class="grid-item"></div>
  </template>
</body>

Please signup or login to give your own answer.

Click here to cancel reply.

How to use the mouseover and mouseout events to change background color of all of the generated divs/grid-items – Jquery

Answers