Date.prototype.AddDays = function (days) {
    days = parseInt(days, 10);
    return new Date(this.valueOf() + 1000 * 60 * 60 * 24 * days);
}

例子

var dt = new Date();
console.log(dt.AddDays(-30));
console.log(dt.AddDays(-10));
console.log(dt.AddDays(-1));
console.log(dt.AddDays(0));
console.log(dt.AddDays(1));
console.log(dt.AddDays(10));
console.log(dt.AddDays(30));

结果

2017-09-03T15:01:37.213Z
2017-09-23T15:01:37.213Z
2017-10-02T15:01:37.213Z
2017-10-03T15:01:37.213Z
2017-10-04T15:01:37.213Z
2017-10-13T15:01:37.213Z
2017-11-02T15:01:37.213Z

两种方法:

1:

var a = new Date()
// no_of_days is an integer value
var b = new Date(a.setTime(a.getTime() + no_of_days * 86400000)

2:类似上述方法

var a = new Date()
// no_of_days is an integer value
var b = new Date(a.setDate(a.getDate() + no_of_days)

通过原生JS，添加一天你可以做以下事情:

let date = new Date(); // today
date.setDate(date.getDate() + 1) // tomorrow

另一种选择是使用矩库:

const date = moment().add(14, "days").toDate()

最简单的方法是转换为毫秒，然后加上1000*60*60*24毫秒，例如:

var tomorrow = new Date(today.getTime()+1000*60*60*24);

结果是表示明天日期的字符串。使用new Date()获取今天的日期，使用Date. getdate()和Date. setdate()添加一天，并将Date对象转换为字符串。

  const tomorrow = () => {
      let t = new Date();
      t.setDate(t.getDate() + 1);
      return `${t.getFullYear()}-${String(t.getMonth() + 1).padStart(2, '0')}-${String(
        t.getDate()
      ).padStart(2, '0')}`;
    };
    tomorrow();

 Date.prototype.AddDays = function (days) {
    days = parseInt(days, 10);
    return new Date(this.valueOf() + 1000 * 60 * 60 * 24 * days);
}

例子

var dt = new Date();
console.log(dt.AddDays(-30));
console.log(dt.AddDays(-10));
console.log(dt.AddDays(-1));
console.log(dt.AddDays(0));
console.log(dt.AddDays(1));
console.log(dt.AddDays(10));
console.log(dt.AddDays(30));

结果

2017-09-03T15:01:37.213Z
2017-09-23T15:01:37.213Z
2017-10-02T15:01:37.213Z
2017-10-03T15:01:37.213Z
2017-10-04T15:01:37.213Z
2017-10-13T15:01:37.213Z
2017-11-02T15:01:37.213Z