Validating a ISO 8601 date using moment.js

Not sure why Praveen's example works in jsfiddle, but the reason your sample doesn't work is because the format isn't YYYY-MM-DD. It includes the time as well, so it's considered invalid. If you try it without the time in the date, it returns true.

Try this instead:
moment("2011-10-10T14:48:00", "YYYY-MM-DDTHH:mm:ss", true).isValid()

Okay, I found it.

As per the documentation,

As of version 2.3.0, you may specify a boolean for the last argument to make Moment use strict parsing. Strict parsing requires that the format and input match exactly

because you use strict operation, it returns false. To overcome that use below code:

alert(moment("2011-10-10T14:48:00", "YYYY-MM-DDTHH:mm:ss", true).isValid())
//This will return true

demo1

If you remove the strict parsing,

alert(moment("2011-10-10T14:48:00", "YYYY-MM-DD").isValid())
//This will return true

demo2

To avoid using string pattern as a second argument, you can just call:

moment("2011-10-10T14:48:00", moment.ISO_8601).isValid() // true
moment("2016-10-13T08:35:47.510Z", moment.ISO_8601).isValid() // true