Q Explain onerror event in javascript.
Answer:
The onerror event handler in JavaScript is used to handle errors that occur during the loading of external resources such as images, scripts, or stylesheets. When an error occurs while loading a resource, the onerror event is triggered, and you can use it to execute a custom JavaScript function to handle the error.
Here's a basic example:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>onerror Example</title>
</head>
<body>
<img src="nonexistent-image.jpg" onerror="handleError()">
<script>
function handleError() {
alert('Error loading image!');
}
</script>
</body>
</html>
In this example:
- The
<img>element attempts to load an image (nonexistent-image.jpg) that doesn't exist. - The
onerrorattribute is set to the JavaScript functionhandleError. - When an error occurs during the image loading (because the image is not found), the
handleErrorfunction is called.
You can apply the same concept to other elements, such as <script> or <link> tags for handling errors in loading JavaScript or CSS files.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>onerror Example</title>
</head>
<body>
<script src="nonexistent-script.js" onerror="handleError()"></script>
<style onerror="handleError()">
/* This will intentionally cause an error */
.nonexistent-class {
color: red;
}
</style>
<script>
function handleError() {
alert('Error loading resource!');
}
</script>
</body>
</html>
In these examples, if the resource specified in the src or href attribute cannot be loaded, the onerror event is triggered, and the handleError function is called to handle the error.
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