mattermost-mobile/app/utils/datetime.ts

// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

export function isSameDay(a: Date, b: Date = new Date()): boolean {
    return a.getDate() === b.getDate() && isSameMonth(a, b);
}

export function isSameMonth(a: Date, b: Date = new Date()): boolean {
    return a.getMonth() === b.getMonth() && isSameYear(a, b);
}

export function isSameYear(a: Date, b: Date = new Date()): boolean {
    return a.getFullYear() === b.getFullYear();
}
export function isYesterday(date: Date): boolean {
    const yesterday = new Date();
    yesterday.setDate(yesterday.getDate() - 1);

    return isSameDay(date, yesterday);
}