d289aa621bcc9429338145e3f4546db87e97004cc8de6a1d4e833c659cd4e3ac

Source Code:

/**
 * Cocoon WordPress Theme
 * @author: yhira
 * @author: technote-space
 * @link: https://wp-cocoon.com/
 * @license: http://www.gnu.org/licenses/gpl-2.0.html GPL v2 or later
 * @description「Passive Event Listener を使用してサイトでのスクロール パフォーマンスを向上させる」への対応 (https://developers.google.com/web/tools/lighthouse/audits/passive-event-listeners?hl=ja)
 */
(function () {
    // https://stackoverflow.com/questions/14439903/how-can-i-detect-device-touch-support-in-javascript
    const isTouchSupported = 'ontouchstart' in window ||
        window.DocumentTouch && document instanceof window.DocumentTouch ||
        navigator.maxTouchPoints > 0 ||
        window.navigator.msMaxTouchPoints > 0;

    if (isTouchSupported) {
        // https://github.com/WICG/EventListenerOptions/blob/gh-pages/explainer.md#feature-detection
        let supportsPassive = false;
        try {
            let opts = Object.defineProperty({}, 'passive', {
                get: function () {
                    supportsPassive = true;
                }
            });
            window.addEventListener("testPassive", null, opts);
            window.removeEventListener("testPassive", null, opts);
        } catch (e) {
        }

        if (supportsPassive) {
            // https://stackoverflow.com/questions/36675693/eventtarget-interface-in-safari
            const target = window.EventTarget || Element;
            const originalAddEventListener = target.prototype.addEventListener;
            target.prototype.addEventListener = function (type, listener, options) {
                if ('wheel' === type || 'mousewheel' === type || 'touchstart' === type || 'touchmove' === type) {
                    options = options || {};
                    options.passive = true;
                }
                originalAddEventListener.call(this, type, listener, options);
            };
        }
    }
})();