valueOf < Date < JavaScript

The valueOf() method of the Date object returns the number of milliseconds for the date since the epoch, which is defined as the midnight at the beginning of January 1, 1970, UTC.

    
    const date = new Date(Date.UTC(96, 1, 2, 3, 4, 5));

    const date1 = date.valueOf();

    console.log(date1);
    // 823230245000

    const date2 = new Date('02 March 2010 03:04:05 GMT');

    const date3 = date2.valueOf();

    console.log(date3);
    // 1267499045000