moment.js validating invalid date "2013-10-311"

Question

Running moment.js, 2.2.1

moment("2010-10-319", ["YYYY-MM-DD"]).isValid()

... returns true, and the moment object would be set to 31 October 2010. The parser seems to strip extraneous characters of any sort:

moment("2010-10-31a", ["YYYY-MM-DD"]).isValid(); // true

Curiouser, if you add additional format choices, then the "stripping" becomes limited to only one character! (Shouldn't the format strings tests be ORed?)

moment("2010-10-319", ["MM/DD/YYYY", "MM-DD-YYYY", "YYYY-MM-DD"]).isValid(); // true
moment("2010-10-3199", ["MM/DD/YYYY", "MM-DD-YYYY", "YYYY-MM-DD"]).isValid(); // false (!!!)

Is this behaviour by design? I'm not getting why.

EDIT: A commenter found another case where extra characters beyond one are, indeed, stripped:

moment("2010-10-319qr", ["MM/DD/YYYY", "MM-DD-YYYY", "YYYY-MM-DD"]).isValid(); // true (!)

Here is is in action: http://jsfiddle.net/grahampcharles/r42jg/6/ (updated with new case)

Answer 1

Moment.js version 2.3.0 added strict parsing.

moment("2010-10-319", ["YYYY-MM-DD"]).isValid();       // true
moment("2010-10-319", ["YYYY-MM-DD"], true).isValid(); // false

moment("2010-10-31a", ["YYYY-MM-DD"]).isValid();       // true
moment("2010-10-31a", ["YYYY-MM-DD"], true).isValid(); // false

var formats = ["MM/DD/YYYY", "MM-DD-YYYY", "YYYY-MM-DD"];

moment("2010-10-319",  formats).isValid(); // true
moment("2010-10-3199", formats).isValid(); // false

moment("2010-10-319",  formats, true).isValid(); // false
moment("2010-10-3199", formats, true).isValid(); // false

moment("2010-10-319qr", formats).isValid();       // true
moment("2010-10-319qr", formats, true).isValid(); // false

Answer 2

create an Issue on the Git Repository from momentjs https://github.com/moment/moment/ the best way to handle this error.