const weekDays = ['lundi', 'mardi', 'mercredi', 'jeudi', 'vendredi', 'samedi', 'dimanche']

interface Date {
    getWeekDay(): string,
    toSQLDate(): string,
}

Date.prototype.toSQLDate = function (): string {
    return (new Date(this)).toISOString().split('T')[0]
}

Date.prototype.getWeekDay = function () {
    const dayIndex = this.getDay() === 0 ? 6 : this.getDay() - 1
    return weekDays[dayIndex]
}