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ViewsUndifined error after switching through images in Javascript
I am trying to create a website with one picture in the middle that changes after a given time. However after running through the loop once, no picture is shown for a short while and my console shows:
Shortly after, it switches through the images again. But having the image dissapear for a short while is a no go.
My Javascript looks like this:
var allPictures = new Array();
var index = 0;
allPictures[0] = "imgA.jpg";
allPictures[1] = "imgB.jpg";
allPictures[2] = "imgC.jpg";
addEventListener("load",() => {
setInterval( function() {
changeImage()
}, 500);
});
function changeImage() {
document.getElementById("galleryPicture").src = allPictures[index];
if (index < allPictures.length) {
index += 1;
} else if (index >= allPictures.length) {
index = 0;
}
}
My HTML looks like this:
<!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">
<link rel="stylesheet" href="main.css">
<title>Website</title>
</head>
<body>
<script src="pictureSwapScript.js"></script>
<div class="galleryPicture">
<img id= "galleryPicture" src="imgA.jpg">
</div>
</body>
</html>
2 answers
Answer question0
The problem is the condition used to increment index, it will get outside the boundaries of the array.
Replace it with
if (index >= allPictures.length - 1) {
index = 0;
} else {
index += 1;
}
There are other minute improvements that can benefit your code, among which the most obvious to me is replacing:
setInterval( function() {
changeImage()
}, 500);
with just
setInterval(changeImage, 500);
0
Below code solves your usecase.
function changeImage() {
if (index < allPictures.length - 1) {
index += 1;
} else if (index >= allPictures.length - 1) {
index = 0;
}
document.getElementById("galleryPicture").src = allPictures[index];
}
You were trying to compare index value with length, index always starts from 0. Hence you will have to decrease length by 1 because length starts from 1