function initSyntaxHighlighting() {
  // code
}

function loadScripts() {
    const scripts = [
        {
            src: 'https://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/highlight.min.js',
            callback: initSyntaxHighlighting
        }
    ];

    scripts.forEach(function(script) {
        const elt = document.createElement('script');
        elt.setAttribute('async', '');
        elt.setAttribute('defer', '');
        elt.setAttribute('src', script.src);
        elt.addEventListener('load', script.callback, true);

        document.head.appendChild(elt);
    });
}
loadScripts()