moment().diff(Moment|String|Number|Date|Array);
moment().diff(Moment|String|Number|Date|Array, String);
moment().diff(Moment|String|Number|Date|Array, String, Boolean);
要获取以毫秒为单位的差异，则像使用 moment#from 一样使用 moment#diff。
var a = moment([2007, 0, 29]);
var b = moment([2007, 0, 28]);
a.diff(b) // 86400000
要获取另一个度量单位中的差异，则将该度量作为第二个参数传入。
var a = moment([2007, 0, 29]);
var b = moment([2007, 0, 28]);
a.diff(b, 'days') // 1
要获取两个时刻之间的差值的时长，则可以将 diff 作为参数传给 moment#duration。
有关更多信息，参阅 moment#duration 上的文档。
支持的度量有 years、months、weeks、days、hours、minutes 和 seconds。
为了便于开发，从 2.0.0 版本开始支持单数形式。
1.1.1 版本中提供了毫秒以外的度量单位。
默认情况下，moment#diff 会将结果截断为零个小数位，并返回一个整数。
如果需要浮点数，则将 true 作为第三个参数传入。
在 2.0.0 之前，moment#diff 返回的数字会四舍五入到最接近的整数，而不是截断的数字。
var a = moment([2008, 9]);
var b = moment([2007, 0]);
a.diff(b, 'years'); // 1
a.diff(b, 'years', true); // 1.75
如果该时刻早于传给 moment.fn.diff 的时刻，则返回值为负数。
var a = moment();
var b = moment().add(1, 'seconds');
a.diff(b) // -1000
b.diff(a) // 1000
考虑这一点的一种简单方法是将 .diff( 替换为减号运算符。
// a < b
a.diff(b) // a - b < 0
b.diff(a) // b - a > 0
月份和年份的差异
moment#diff 对月份和年份的差异进行一些特殊处理。
它做了一些优化，以确保具有相同日期的两个月始终是整数。
因此，1月15日至2月15日应该恰好是1个月。
2月28日至3月28日应该恰好是1个月。
2011年2月28日至2012年2月28日应该恰好是1年。
对月份和年份的差异的更改于 2.0.0。 从 2.9.0 版本开始，diff 还支持季度单位。
moment().diff(Moment|String|Number|Date|Array);
moment().diff(Moment|String|Number|Date|Array, String);
moment().diff(Moment|String|Number|Date|Array, String, Boolean);
To get the difference in milliseconds, use moment#diff like you would use moment#from.
var a = moment([2007, 0, 29]);
var b = moment([2007, 0, 28]);
a.diff(b) // 86400000
To get the difference in another unit of measurement, pass that measurement as the second argument.
var a = moment([2007, 0, 29]);
var b = moment([2007, 0, 28]);
a.diff(b, 'days') // 1
To get the duration of a difference between two moments, you can pass diff as an argument into moment#duration. See the docs on moment#duration for more info.
The supported measurements are years, months, weeks, days, hours, minutes, and seconds. For ease of development, the singular forms are supported as of 2.0.0. Units of measurement other than milliseconds are available in version 1.1.1.
By default, moment#diff will truncate the result to zero decimal places, returning an integer. If you want a floating point number, pass true as the third argument. Before 2.0.0, moment#diff returned a number rounded to the nearest integer, not a truncated number.
var a = moment([2008, 9]);
var b = moment([2007, 0]);
a.diff(b, 'years'); // 1
a.diff(b, 'years', true); // 1.75
If the moment is earlier than the moment you are passing to moment.fn.diff, the return value will be negative.
var a = moment();
var b = moment().add(1, 'seconds');
a.diff(b) // -1000
b.diff(a) // 1000
An easy way to think of this is by replacing .diff( with a minus operator.
// a < b
a.diff(b) // a - b < 0
b.diff(a) // b - a > 0
Month and year diffs
moment#diff has some special handling for month and year diffs. It is optimized to ensure that two months with the same date are always a whole number apart.
So Jan 15 to Feb 15 should be exactly 1 month.
Feb 28 to Mar 28 should be exactly 1 month.
Feb 28 2011 to Feb 28 2012 should be exactly 1 year.
See more discussion on the month and year diffs here
This change to month and year diffs was made in 2.0.0. As of version 2.9.0 diff also support quarter unit.