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Please try...<br />
<br />
IF ( isNAN(lastvisit) == False ) <br />
--- VALID DATE
</div>


<div>
I don't think that will work as the date object returns something like this Fri Dec 01 2017 22:01:37 GMT-0800 (Pacific Standard Time)
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So what you need in return.
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Just trying to find the best way to detect an invalid date.
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JavaScript is very standardized across browsers. &nbsp;There is no reason to think there will be differences. &nbsp;Your biggest problem is that the date() function will try to return something that makes sense... even if it doesn't. &nbsp;On this page <a href="https://www.w3schools.com/js/tryit.asp?filename=tryjs_date_new_string" rel="ugc">https://www.w3schools.com/js/tryit.asp?filename=tryjs_date_new_string</a>&nbsp;you can try all kinds of entries to see what happens. &nbsp;When I entered '1923', it returned &quot;Sun Dec 31 1922 16:00:00 GMT-0800 (Pacific Standard Time)&quot;.
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Hi Julian,<br />
Wouldn't that <b>always</b> be true since you are comparing the exact same thing or was there a typo???<br />
<br />
if (dt.getTime() === dt.getTime())
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It is one of the things about the invalid Date - getTime when compared to itself does not evaluate to true. Tested back to IE9 and all other browsers.
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<div class="content wysiwyg-content">
I'm trying to figure out if different browsers will return different messages/errors when a string is passed into a date function as per the below example where last[0] = &quot;new visit&quot;:<br />
<br />

<pre><code class="code-1 nolinks" id="code-10-29071495-1"><span>var lastVisit = new Date(last[0]);</span>
</code></pre>
<br />
Chrome returns &quot;<b>Invalid Date</b>&quot; but not sure how robust this will be across all browsers if I'm using:<br />
<br />

<pre><code class="code-1 nolinks" id="code-10-29071495-2"><span>if(lastvisit != &quot;Invalid Date&quot;)</span>
</code></pre>
<br />
I'm not sure if there is a better way to detect if I got a date format back or an invalid date? I can't do anything about the string being passed. It will happen the initial session a user hits the site.
</div>
</div>


I'm trying to figure out if different browsers will return different messages/errors when a string is passed into a date function as per the below example where last[0] = "new visit":

(CODE)

Chrome returns "Invalid Date" but not sure how robust this will be across all browsers if I'm using:

(CODE)

I'm not sure if there is a better way to detect if I got a date format back or an invalid date? I can't do anything about the string being passed. It will happen the initial session a user hits the site.

JavaScript - Best way to Detect Invalid Date Across Multiple Browsers

Web development includes all aspects of presenting content on intranets and the Internet, including delivery development, protocols, languages and standards, server software, browser clients, databases and multimedia generation.

Web Development

Chrome is a free web browser created by Google. Originally released in 2008, it has grown to become the most used desktop web browser (as of October 2016).

Chrome

JavaScript is a dynamic, object-based language commonly used for client-side scripting in web browsers. Recently, server side JavaScript frameworks have also emerged. JavaScript runs on nearly every operating system and  in almost every mainstream web browser.

JavaScript

Web browsers are applications used primarily to display documents, files and media from the Internet, identified by a Uniform Resource Identifier (URI) that can be a page, image, video or other file. Some browsers require the use of add-ons or extensions to safely render the information they receive; others have systems built into them to perform the same functions.