js日期前一天

function getPreviousDay(date) {
    let previousDay = new Date(date);
    previousDay.setDate(previousDay.getDate() - 1);
    return previousDay;
}

// 使用示例
let today = new Date();
let yesterday = getPreviousDay(today);
console.log(yesterday);

function getPreviousDay(date) {
    let year = date.getFullYear();
    let month = date.getMonth();
    let day = date.getDate();

    // 减去一天
    day -= 1;

    // 处理月份和年份的变化
    if (day < 1) {
        month -= 1;
        if (month < 0) {
            month = 11;
            year -= 1;
        }
        let daysInMonth = new Date(year, month + 1, 0).getDate();
        day = daysInMonth;
    }

    return new Date(year, month, day);
}

// 使用示例
let today = new Date();
let yesterday = getPreviousDay(today);
console.log(yesterday);

function getPreviousDayUTC(date) {
    let year = date.getUTCFullYear();
    let month = date.getUTCMonth();
    let day = date.getUTCDate();

    // 减去一天
    day -= 1;

    // 处理月份和年份的变化
    if (day < 1) {
        month -= 1;
        if (month < 0) {
            month = 11;
            year -= 1;
        }
        let daysInMonth = new Date(Date.UTC(year, month + 1, 0)).getUTCDate();
        day = daysInMonth;
    }

    return new Date(Date.UTC(year, month, day));
}

// 使用示例
let today = new Date();
let yesterday = getPreviousDayUTC(today);
console.log(yesterday);