Anki script - insert Script

function insertScript(path, altURL) {
    return new Promise((resolve, reject) => {
        let scriptExists = false;

        // Check if script with the same src already exists
        const scripts = document.head.getElementsByTagName('script');
        for (let i = 0; i < scripts.length; i++) {
            if (scripts[i].src === path) {
                scriptExists = true;
                scripts[i].onload = resolve;
                scripts[i].onerror = () => {
                    // If the script fails to load, reload it from altURL
                    let script_online = document.createElement("script");
                    script_online.onload = resolve;
                    script_online.onerror = reject;
                    script_online.src = altURL;
                    scripts[i].parentNode.replaceChild(script_online, scripts[i]);
                }
                // Reload the script by setting its src to empty string and then to original path
                scripts[i].src = '';
                scripts[i].src = path;
                break;
            }
        }

        if (!scriptExists) {
            // If script doesn't exist, create a new script element
            let script_local = document.createElement("script");
            script_local.onload = resolve;
            script_local.onerror = () => {
                // If the script fails to load, create a new script element with altURL
                let script_online = document.createElement("script");
                script_online.onload = resolve;
                script_online.onerror = reject;
                script_online.src = altURL;
                document.head.appendChild(script_online);
            }
            script_local.src = path;
            document.head.appendChild(script_local);
        }
    });
}