Check if date is a valid one

问题:

Following is the scenario:

I have a String date and a date format which is different. Ex.:
date: 2016-10-19
dateFormat: "DD-MM-YYYY".

I need to check if this date is a valid date.

I have tried following things

var d = moment("2016-10-19",dateFormat);

d.isValid() is returning false every time. Does not Moment.js parse the date in the given format?

Then I tried to format the date in DD-MM-YYYY first and then pass it to Moment.js:

var d = moment("2016-10-19").format(dateFormat);
var date = moment(d, dateFormat);

Now date.isValid() is giving me the desired result, but here the Moment.js date object is created twice. How can I avoid this? Is there a better solution?

FYI I am not allowed to change the dateFormat.

回答1:

Was able to find the solution. Since the date I am getting is in ISO format, only providing date to moment will validate it, no need to pass the dateFormat.

var date = moment("2016-10-19");

And then date.isValid() gives desired result.

回答2:

var date = moment('2016-10-19', 'DD-MM-YYYY', true);

You should add a third argument when invoking moment that enforces strict parsing. Here is the relevant portion of the moment documentation http://momentjs.com/docs/#/parsing/string-format/ It is near the end of the section.

回答3:

Here you go: Working Fidddle

$(function(){
  var dateFormat = 'DD-MM-YYYY';
  alert(moment(moment("2012-10-19").format(dateFormat),dateFormat,true).isValid());
});

回答4:

I use moment along with new Date to handle cases of undefined data values:

const date = moment(new Date("2016-10-19"));

because of: moment(undefined).isValid() == true

where as the better way: moment(new Date(undefined)).isValid() == false

回答5:

Try this one. It is not nice but it will work as long as the input is constant format from your date picker.

It is badDate coming from your picker in this example

https://jsfiddle.net/xs8tvox9/

var dateFormat = 'DD-MM-YYYY'
var badDate = "2016-10-19";

var splittedDate = badDate.split('-');

if (splittedDate.length == 3) {
  var d = moment(splittedDate[2]+"-"+splittedDate[1]+"-"+splittedDate[0], dateFormat);
  alert(d.isValid())
} else {
  //incorrectFormat
}