hexo-theme-butterfly/layout/includes/third-party/abcjs.pug

script.
    function abcjsInit() {
        function abcjsFn() {
            for (let abcContainer of document.getElementsByClassName("abc-music-sheet")) {
                ABCJS.renderAbc(abcContainer, abcContainer.innerHTML, {responsive: 'resize'});
            }
        }
        if (typeof ABCJS === 'object') {
            abcjsFn();
        } else {
            getScript('!{url_for(theme.asset.abcjs_basic_js)}')
                .then(() => {
                    abcjsFn();
                });
        }
    }

    document.addEventListener('DOMContentLoaded', abcjsInit);