I had to work with jQuery lately (2.x.y) and I was quite disappointed there was no Promise.allSettled-like implementation in its $.Deferred object api, so here it is...

deferredsAllSettled.js

const deferredsAllSettled = deferreds => {
    const settlements = [];

    deferreds.forEach(deferred => {
        const settlement = jQuery.Deferred();
        
        deferred.always(settlement.resolve);

        settlements.push(settlement);
    });

    const returnedDeferred = $.Deferred();

    jQuery.when
        .apply(jQuery, settlements)
        .then(() =>
            returnedDeferred.resolve(
                deferreds.map(deferred => deferred.promise())
            )
        );

    return returnedDeferred.promise();
};