const date_1999 = new Date("1999-01-01")
const date_1999_ = new Date("1999-01-01")
const date_2000 = new Date("2000-01-01")
const date_2001 = new Date("2001-01-01")

console.log(date_1999 < date_2000) // true
console.log(date_1999_ < date_2001) // true
console.log(date_1999 < date_1999) // false
console.log(date_1999 < date_1999_) // false
console.log(date_1999 == date_1999) // true
console.log(date_1999 == date_1999_) // false
console.log(date_1999 <= date_1999_) // true