/inc/plugins/mybb_mobile/mobile.js or
/images/mobile_theme/jquery.mobile.js If you’re using the plugin: mybb mobile theme
let touchstartX = 0; document.addEventListener('touchstart', e => { touchstartX = e.changedTouches[0].screenX; }); document.addEventListener('touchend', e => { const endX = e.changedTouches[0].screenX; if (endX < touchstartX - 50) history.back(); }); In the mobile theme’s CSS file (e.g., mobile.css ): /inc/plugins/mybb_mobile/mobile