willcore.uicore/client/helpers/lazyImport.js

Base extendable UI html framework.

function lazyImport(url) {
    try { 
        return (new Function(`return import("${url}")`))();
    } catch (err) {
    }

    function toAbsoluteURL(url) {
        const a = document.createElement("a");
        a.setAttribute("href", url);    
        return a.cloneNode(false).href; 
    }

    return new Promise((resolve, reject) => {
        const vector = "$importModule$" + Math.random().toString(32).slice(2);
        const script = document.createElement("script");
        const destructor = () => {
            delete window[vector];
            script.onerror = null;
            script.onload = null;
            script.remove();
            URL.revokeObjectURL(script.src);
            script.src = "";
        };
        script.defer = "defer";
        script.type = "module";
        script.onerror = () => {
            reject(new Error(`Failed to import: ${url}`));
            destructor();
        };
        script.onload = () => {
            resolve(window[vector]);
            destructor();
        };
        const absURL = toAbsoluteURL(url);
        const loader = `import * as m from "${absURL}"; window.${vector} = m;`; 
        const blob = new Blob([loader], { type: "text/javascript" });
        script.src = URL.createObjectURL(blob);

        document.head.appendChild(script);
    });
};

export { lazyImport };