FileReader: abort event
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Note: This feature is available in Web Workers.
The abort event of the FileReader interface is fired when a read has been aborted: for instance because the program called FileReader.abort().
This event is not cancelable and does not bubble.
Syntax
Use the event name in addEventListener():
js
addEventListener("abort", (event) => { })
Alternatively, assign to the event handler property of the interface:
js
onabort = (event) => { }
Event type
A ProgressEvent. Inherits from Event.
Examples
Live example
HTML
html
<div class="example">
<div class="file-select">
<label for="avatar">Choose a profile picture:</label>
<input
type="file"
id="avatar"
name="avatar"
accept="image/png, image/jpeg" />
</div>
<img src="" class="preview" height="200" alt="Image preview" />
<div class="event-log">
<label for="eventLog">Event log:</label>
<textarea readonly class="event-log-contents" id="eventLog"></textarea>
</div>
</div>
JavaScript
js
const fileInput = document.querySelector('input[type="file"]');
const preview = document.querySelector("img.preview");
const eventLog = document.querySelector(".event-log-contents");
const reader = new FileReader();
function handleEvent(event) {
eventLog.textContent += `${event.type}: ${event.loaded} bytes transferred\n`;
if (event.type === "load") {
preview.src = reader.result;
}
}
function addListeners(reader) {
reader.addEventListener("loadstart", handleEvent);
reader.addEventListener("load", handleEvent);
reader.addEventListener("loadend", handleEvent);
reader.addEventListener("progress", handleEvent);
reader.addEventListener("error", handleEvent);
reader.addEventListener("abort", handleEvent);
}
function handleSelected(e) {
eventLog.textContent = "";
const selectedFile = fileInput.files[0];
if (selectedFile) {
addListeners(reader);
reader.readAsDataURL(selectedFile);
}
reader.abort();
}
fileInput.addEventListener("change", handleSelected);
Result
Specifications
| Specification |
|---|
| File API # dfn-abort-event |
| File API # dfn-onabort |