js date dateadd

function addDays(date, days) {
    const result = new Date(date);
    result.setDate(result.getDate() + days);
    return result;
}

// 示例
const today = new Date();
console.log("Today:", today);
const tomorrow = addDays(today, 1);
console.log("Tomorrow:", tomorrow);

function addMonths(date, months) {
    const result = new Date(date);
    result.setMonth(result.getMonth() + months);
    return result;
}

// 示例
const firstDayOfMonth = new Date(2023, 0, 1); // January 1, 2023
console.log("First day of month:", firstDayOfMonth);
const firstDayOfNextMonth = addMonths(firstDayOfMonth, 1);
console.log("First day of next month:", firstDayOfNextMonth);

function addYears(date, years) {
    const result = new Date(date);
    result.setFullYear(result.getFullYear() + years);
    return result;
}

// 示例
const newYear = new Date(2023, 0, 1); // January 1, 2023
console.log("New Year:", newYear);
const nextNewYear = addYears(newYear, 1);
console.log("Next New Year:", nextNewYear);

const date = new Date(2023, 0, 31); // January 31, 2023
date.setMonth(date.getMonth() + 1); // 自动调整为 February 28, 2023
console.log(date); // 输出: 2023-02-28T00:00:00.000Z