scriptInterceptor.js

const createElementBackup = document.createElement;
function myCreateElement(tagName: string, options?: ElementCreationOptions): HTMLElement {
    const scriptElt = createElementBackup.call(document, tagName, options);
    if (tagName.toLowerCase() !== 'script') {
        return scriptElt;
    }
    const originalSetAttribute = scriptElt.setAttribute.bind(scriptElt);
    Object.defineProperties(scriptElt, {
        'src': {
            get() {
                return scriptElt.getAttribute('src');
            },
            set(value: string) {
                // This is where the magic happends
                const mutated = urlMutator(value);
                originalSetAttribute('src', mutated || value);
                return true;
            }
        }
    });
    return scriptElt;
}

document.createElement = myCreateElement;