vscode/extensions/markdown/preview-src/loading.ts

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/
import { getSettings } from './settings';

const unloadedStyles: string[] = [];

const settings = getSettings();

const onStyleLoadError = (event: any) => {
	const source = event.target.dataset.source;
	unloadedStyles.push(source);
};

window.addEventListener('DOMContentLoaded', () => {
	for (const link of document.getElementsByClassName('code-user-style') as HTMLCollectionOf<HTMLElement>) {
		if (link.dataset.source) {
			link.onerror = onStyleLoadError;
		}
	}
});

window.addEventListener('load', () => {
	if (!unloadedStyles.length) {
		return;
	}
	window.parent.postMessage({
		type: 'command',
		source: settings.source,
		body: {
			command: '_markdown.onPreviewStyleLoadError',
			args: [unloadedStyles]
		}
	}, '*');
});