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Content script context event #1778

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Content script context event #1778

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ed88d95
Unregisters listeners when invalid
sleekslush Jun 30, 2025
2d30f75
Explicit invalidate handler
sleekslush Jun 30, 2025
3101e9a
Removes options .. unnecessary in this context
sleekslush Jun 30, 2025
47580a7
uses the formatted event name
sleekslush Jun 30, 2025
011342e
Simpler event handler
sleekslush Jun 30, 2025
f24fb95
fix comment
sleekslush Jun 30, 2025
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66 changes: 12 additions & 54 deletions packages/wxt/src/utils/content-script-context.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -39,27 +39,14 @@ import { createLocationWatcher } from './internal/location-watcher';
* ```
*/
export class ContentScriptContext implements AbortController {
private static SCRIPT_STARTED_MESSAGE_TYPE = getUniqueEventName(
'wxt:content-script-started',
);

private isTopFrame = window.self === window.top;
private abortController: AbortController;
private locationWatcher = createLocationWatcher(this);
private receivedMessageIds = new Set<string>();

constructor(
private readonly contentScriptName: string,
public readonly options?: Omit<ContentScriptDefinition, 'main'>,
) {
this.abortController = new AbortController();

if (this.isTopFrame) {
this.listenForNewerScripts({ ignoreFirstEvent: true });
this.stopOldScripts();
} else {
this.listenForNewerScripts();
}
}

get signal() {
Expand Down Expand Up @@ -221,8 +208,19 @@ export class ContentScriptContext implements AbortController {
if (this.isValid) this.locationWatcher.run();
}

const eventType = type.startsWith('wxt:') ? getUniqueEventName(type) : type

target.addEventListener?.(
eventType,
() => this.isInvalid, // signals the abort controller when invalid
{
capture: true,
signal: this.signal,
},
);

target.addEventListener?.(
type.startsWith('wxt:') ? getUniqueEventName(type) : type,
eventType,
handler,
{
...options,
Expand All @@ -241,46 +239,6 @@ export class ContentScriptContext implements AbortController {
`Content script "${this.contentScriptName}" context invalidated`,
);
}

stopOldScripts() {
// Use postMessage so it get's sent to all the frames of the page.
window.postMessage(
{
type: ContentScriptContext.SCRIPT_STARTED_MESSAGE_TYPE,
contentScriptName: this.contentScriptName,
messageId: Math.random().toString(36).slice(2),
},
'*',
);
}

verifyScriptStartedEvent(event: MessageEvent) {
const isScriptStartedEvent =
event.data?.type === ContentScriptContext.SCRIPT_STARTED_MESSAGE_TYPE;
const isSameContentScript =
event.data?.contentScriptName === this.contentScriptName;
const isNotDuplicate = !this.receivedMessageIds.has(event.data?.messageId);
return isScriptStartedEvent && isSameContentScript && isNotDuplicate;
}

listenForNewerScripts(options?: { ignoreFirstEvent?: boolean }) {
let isFirst = true;

const cb = (event: MessageEvent) => {
if (this.verifyScriptStartedEvent(event)) {
this.receivedMessageIds.add(event.data.messageId);

const wasFirst = isFirst;
isFirst = false;
if (wasFirst && options?.ignoreFirstEvent) return;

this.notifyInvalidated();
}
};

addEventListener('message', cb);
this.onInvalidated(() => removeEventListener('message', cb));
}
}

export interface WxtWindowEventMap extends WindowEventMap {
Expand Down