fake Date in devTools for testing

fake_date.js

// Context https://stackoverflow.com/a/72640597/861615

// Save the original `Date` function
const OriginalDate = Date;
const fakeDateArgs = [2022, 5, 3]; // beware month is 0 based
let fakeDate;
// Replace it with our own
Date = function Date(...args) {
    // Called via `new`?
    if (!new.target) {
        // No, just pass the call on
        return OriginalDate(...args);
    }
    // Determine what constructor to call
    const ctor = new.target === Date ? OriginalDate : new.target;
    // Called via `new`
    if (args.length !== 0) {
        // Date constructor arguments were provided, just pass through
        return Reflect.construct(ctor, args);
    }
    // It's a `new Date()` call, mock the date we want; in this
    fakeDate = Reflect.construct(ctor, fakeDateArgs);
    return fakeDate;
};
// Make our replacement look like the original (which has `length = 7`)
// You can't assign to `length`, but you can redefine it
Object.defineProperty(Date, "length", {
    value: OriginalDate.length,
    configurable: true
});

Object.defineProperty(Date, "now", {
    value: () => fakeDate?.getTime(),
    configurable: true
});