Rocket.Chat/apps/meteor/client/lib/meteorRuntimeConfig.ts

// Single point of access to the `__meteor_runtime_config__` globals that
// Meteor's bootloader injects into the page (ROOT_URL and
// ROOT_URL_PATH_PREFIX). Consumers must read/write through these helpers so
// the eventual replacement (a static config injected at build time) is a
// single-file swap.

const getConfig = (): { ROOT_URL?: string; ROOT_URL_PATH_PREFIX?: string } | undefined => {
	if (typeof __meteor_runtime_config__ !== 'object' || __meteor_runtime_config__ === null) {
		return undefined;
	}
	return __meteor_runtime_config__;
};

export const getRootUrl = (): string | undefined => getConfig()?.ROOT_URL;

export const getRootUrlPathPrefix = (): string => getConfig()?.ROOT_URL_PATH_PREFIX ?? '';

export const setRootUrl = (value: string): void => {
	const config = getConfig();
	if (config) {
		config.ROOT_URL = value;
	}
};