import SpeedTester from 'browser-speed-test';
    /**
     * @param {object} optional - The tester config.
     * @param optional.url Links to resources such as downloaded images for testing.
     * @param optional.fileSize When CROS is disabled, we use the img tag to test, the fileSize is required.
     * @param optional.testFrequency Testing frequency.
     * @param optional.onProgress The testing progress callback function.
     */
    const tester = new SpeedTester({ url });
    tester.start();