How to override fetch in javascript to intercept it

This is an handy script to override fetch and perform some manipulation before the network request starts:

const { fetch: originalFetch } = window;
window.fetch = async (...args) => {
    let [resource, config ] = args;

    if(resource == '/some/route') resource = 'https://www.othercontent.com';

    const response = await originalFetch(resource, config);

    return response
}

The above code is not very useful if you have full control of the server, thus, it is when you need to manipulate a website you don't control at server level, (hint: scraping).