js 判斷昨天，前天，去年

// 判斷是否是昨天
 function isYesterday(time) {
		 const date = new Date();
	     const year = date.getFullYear();
	    const month = date.getMonth() + 1;
	    const day = date.getDate();
	    const today = `${year}/${month}/${day}`; 
        const todayTime = new Date(today).getTime(); // 當天凌晨的時間
        const yesterdayTime = new Date(todayTime - 24 * 60 * 60 * 1000).getTime(); // 昨天凌晨的時間
        return time < todayTime && yesterdayTime <= time;
    }

    console.log(isYesterday(Date.now()));
    console.log(isYesterday(new Date('2019/05/28 10:10').getTime()));
    console.log(isYesterday(new Date('2019/05/27 10:10').getTime()));
// 判斷是否是去年
function isLastYear(time){
    const year = new Date().getFullYear();
    const lastYear = new Date(time).getFullYear();
    return (year - lastYear) === 1;

}
console.log(isLastYear(Date.now()));
console.log(isLastYear(new Date('2019/05/28 10:10').getTime()));
console.log(isLastYear(new Date('2018/05/27 10:10').getTime()));
console.log(isLastYear(new Date('2017/05/27 10:10').getTime()));
    // 判斷是否是前天
function isLastYesterday(time) {
    const twentyFourHours = 24 * 60 * 60 * 1000;
    const fortyEightHours = 24 * 60 * 60 * 1000 * 2;
    const date = new Date();
    const year = date.getFullYear();
    const month = date.getMonth() + 1;
    const day = date.getDate();
    const today = `${year}/${month}/${day}`; 
    const todayTime = new Date(today).getTime(); // 當天凌晨的時間
    const yesterdayTime = new Date(todayTime - twentyFourHours).getTime(); // 昨天凌晨的時間
    const lastYesterdayTime = new Date(todayTime - fortyEightHours).getTime(); // 昨天凌晨的時間
    return time < yesterdayTime && lastYesterdayTime <= time;
}
console.log(isLastYesterday(Date.now()));
console.log(isLastYesterday(new Date('2019/05/28 10:10').getTime()));
console.log(isLastYesterday(new Date('2018/05/27 10:10').getTime()));
console.log(isLastYesterday(new Date('2017/05/27 10:10').getTime()));
console.log(isLastYesterday(new Date('2019/05/27 10:10').getTime()));
console.log(isLastYesterday(new Date('2019/05/23 10:10').getTime()));