javascript - 一起显示昨天和今天的日期 javascript

Question

我想在我的仪表板上同时显示昨天的日期和今天的日期。例如如果今天的日期是2019年6月30日，则应将2019年6月29日显示为昨天，或者如果今天的日期是2019年7月1日，它应该将2019年6月30日显示为昨天日期。

我尝试根据今天的日期计算前一天和日期，但它不会每次都会自动更改。我陷入了循环函数中。

getToday(){

        const monthNames = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];


        var dateToday = new Date().getDate();
        let monthToday = monthNames[new Date().getMonth()];
        let yearToday = new Date().getFullYear();

    }


getYesterday(){
    // var dateToday = new Date().getDate();
    //let dateYesterday = new Date(Date.now() - 86400000).getDate();
    //let monthYesterday = new Date(Date.now() - 86400000).getMonth();
    //console.log(dateYesterday,monthYesterday)



   //another approach I tried following
   var dateToday = new Date().getDate();
   var yesterday = dateToday.setDate(dateToday.getDate() - 1);
}

componentDidMount(){

            this.getToday();
            this.getYesterday();
}

请帮助完成此任务。

Answer 1

您需要:

var d = new Date();
d.setDate(d.getDate() -1);

d 是昨天的日期。

getFullYear()   Get the year as a four digit number (yyyy)
getMonth()  Get the month as a number (0-11)
getDate()   Get the day as a number (1-31)
getHours()  Get the hour (0-23)
getMinutes()    Get the minute (0-59)
getSeconds()    Get the second (0-59)
getMilliseconds()   Get the millisecond (0-999)
getTime()   Get the time (milliseconds since January 1, 1970)
getDay()    Get the weekday as a number (0-6)
Date.now()  Get the time. ECMAScript 5.

示例:

var d = new Date();
d.setDate(d.getDate() -1);
monthYesterday = d.getMonth(); // you get the month of yesterday
yearYesterday = d.getFullYear(); // you get the year of yesterday (format yyyy)