/*
  Copyright 2018 Google LLC

  Use of this source code is governed by an MIT-style
  license that can be found in the LICENSE file or at
  https://opensource.org/licenses/MIT.
*/
import { logger } from 'workbox-core/_private/logger.js';
import { isSupported } from './isSupported.js';
import './_version.js';
/**
 * If the browser supports Navigation Preload, then this will enable it.
 *
 * @param {string} [headerValue] Optionally, allows developers to
 * [override](https://developers.google.com/web/updates/2017/02/navigation-preload#changing_the_header)
 * the value of the `Service-Worker-Navigation-Preload` header which will be
 * sent to the server when making the navigation request.
 *
 * @memberof module:workbox-navigation-preload
 */
function enable(headerValue) {
    if (isSupported()) {
        self.addEventListener('activate', (event) => {
            event.waitUntil(self.registration.navigationPreload.enable().then(() => {
                // Defaults to Service-Worker-Navigation-Preload: true if not set.
                if (headerValue) {
                    self.registration.navigationPreload.setHeaderValue(headerValue);
                }
                if (process.env.NODE_ENV !== 'production') {
                    logger.log(`Navigation preload is enabled.`);
                }
            }));
        });
    }
    else {
        if (process.env.NODE_ENV !== 'production') {
            logger.log(`Navigation preload is not supported in this browser.`);
        }
    }
}
export { enable };