Moment.js - moment（）。format（）创建无效日期？

Question

moment().format() creates a date that is not valid according to moment().isValid()

Here is the example:

> moment.version
"2.14.1"
> moment.locale()
"fr"
> moment().format("ll")
"29 juill. 2016"
> moment("29 juill. 2016", "ll", true).isValid()
false

However if I remove the period in the month it works:

> moment("29 juill 2016", "ll", true).isValid()
true

Or if I disable strict parsing (remove the 3rd parameter) it works:

> moment("29 juill. 2016", "ll").isValid()
true

Why is this? Why doesn't moment().format("ll") create a date that is valid with strict parsing?

Answer 1

I think that's because "ll" is not a valid date formatting, if you will run the moment function and ask for a timestamp ( .valueOf ) you will get a NaN

moment("29 juill 2016", "ll", true).valueOf()
// NaN

You need to provide a valid formatting for the 2nd argument, for your date string it would be "DD MMMM, YYYY"

Also, I think you had a typo in juill , I think it should be juillet

moment.locale("fr")
// "fr"
 moment("29 july, 2016", "DD MMMM, YYYY", true).isValid()
// false
 moment("29 juillet, 2016", "DD MMMM, YYYY", true).isValid()
// true

Answer 2

Answering this myself in case someone else faces the same issue.

This was due to an issue with moment.js version 2.8.1 not parsing custom short month names with periods correctly. This issue is resolved in the later version 2.14.1 .

Here's the example that produces different results in 2.8.1 and 2.14.1

moment.locale("fr", {
  monthsShort: [
    "janv.",
    "févr.",
    "mars",
    "avr.",
    "Mai",
    "juin",
    "juilltest.",
    "août",
    "sept.",
    "oct.",
    "nov.",
    "déc."
  ],
  monthsParseExact: true,
  longDateFormat: {
    LL: "DD MMM YYYY",
    ll: "DD MMM YYYY"
  },

});
console.log(moment.version);
moment.locale('fr');
console.log(moment.locale());
var testDate = '29 juilltest. 2016'; // month name with period in it that matches the custom short name given above
console.log(moment(testDate, "LL", true).isValid());
console.log(moment(testDate, "ll", true).isValid());
console.log(moment.localeData("fr"));

Version 2.8.1: https://jsfiddle.net/3do4ubsj/

2.8.1
fr
false
false

Version 2.14.1: https://jsfiddle.net/pkhcaqmy/

2.14.1
fr
true
true

The commit that fixed it: https://github.com/moment/moment/commit/fc5a352e9ca30e32a96875810604ad981d1442c3

A related issue in moment.js repo: https://github.com/moment/moment/issues/3126