Inject custom script to main page's document.head, used for bypassing Chrome Extension's Content-Scripts Sandbox.

injector.js

'Drink Responsibly, Blackmagic lives here.';

/**
 * Inject custom script to main page's document.head.
 * Used for bypassing Chrome Extension's Content-Scripts Sandbox.
 */
/**
 * @param {{type?: string, src?: string, text?: string}} content
 * @see Microsoft/vscode#22980, "JSDoc comments are ignored for destructured parameters".
 * @see Microsoft/typescript#11597, "Intellisense for object properties defined in multi-line JSDOC comments".
 */
function __inject__({type, src, text}) {
	if (src === undefined && text === undefined) return;
	const _ = document.createElement('script');
	_.async = true;
	if (type !== undefined) _.type = type;
	if (src !== undefined) _.src = src;
	if (text !== undefined) _.appendChild(document.createTextNode(text));
	if (document.head) {
		document.head.appendChild(_);
	} else {  // XXX: Used for `run_at: document_start`.
		document.documentElement.appendChild(_);
	}
}

usage.js

// HACK: BREAKING ContentScripts Sandbox.
__inject__({
	type: 'text/javascript',
	text: `(${ String(__inject__) })({
		type: 'module',
		src: '${ chrome.extension.getURL("wanted_content_script.js") }',
	})`,
});