loadscript.js

// Take from https://github.com/tserkov/vue-plugin-load-script/blob/master/index.js

export default function (src) {
    return new Promise(function (resolve, reject) {
        let shouldAppend = false;
        let el = document.querySelector('script[src="' + src + '"]');
        if (!el) {
            el = document.createElement('script');
            el.type = 'text/javascript';
            el.async = true;
            el.src = src;
            shouldAppend = true;
        }
        else if (el.hasAttribute('data-loaded')) {
            resolve(el);
            return;
        }

        el.addEventListener('error', reject);
        el.addEventListener('abort', reject);
        el.addEventListener('load', function loadScriptHandler() {
            el.setAttribute('data-loaded', true);
            resolve(el);
        });

        if (shouldAppend) document.head.appendChild(el);
    });
};