Checking if a date is valid in javascript [duplicate]

Question

Possible Duplicate:
Detecting an “invalid date” Date instance in JavaScript

Is there is a function IsDate() in javascript?

Brien Foss · Accepted Answer · 2020-11-17 17:14:49Z

215

Try this:

var date = new Date(); console.log(date instanceof Date && !isNaN(date.valueOf()));

This should return true.

UPDATED: Added isNaN check to handle the case commented by Julian H. Lam

edited Nov 17, 2020 at 17:14

Brien Foss

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answered May 14, 2012 at 19:25

Gabriel Jürgens

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10 Comments

Julian H. Lam Over a year ago

new Date('derp') instanceof Date // true

Gabriel Jürgens Over a year ago

@JulianH.Lam I've added a isNaN validation to the valueOf property to handle this case. Thanks!!!

Brian Edwards Over a year ago

Returns true for new Date('06/31/2016') since Javascript converts that to 7/1/2016. Returns false for 06/32/2016 however. Just something to keep in mind. Only drawback.

schmoopy Over a year ago

@JulianH.Lam - but then 'Do NOT Convert Me as a date 1' also returns true

roland Over a year ago

I've actually expanded my example. Even using MomentJS's isValid() function is incorrect. It seems like JavaScript uses the Date.parse function - when it fails to evaluate the text, it just uses the numbers, so new Date('Test 1') evaluates to the same as new Date('1'). The only way to get it working correctly would be either to develop your own string parsing, or you could use date-fns.org - the isValid() function seems to work correctly.

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