Javascript extract date from certain elements with match and regex returns empty array [duplicate]

Question

I want to make a userscript for a website, where I want to extract and select the date in some <td> fields. Example:

<tbody>
<td><img></td>
<td>something</td>
<td>something</td>
...
<td style="text-align:center;">2016-02-10 13:27</td>
<td>something</td>
...
<td>something</td>
</tbody>

There are two things I want to do: 1. compare the date with another stored date (and check if it is later). 2. change the background-color of the <td> element where the date is located.

This is what I have, and it returns an empty array...

var dateArray = [];
$("td").each(function(){
    if(String(this).match(/\d{4}-\d{2}-\d{2} \d{2}:\d{2}/)){
        dateArray.push(this);
    }
});

What is wrong and/or what could I do in a better way?

Thanks!

I guess this will be a jQuery object, what you do you expect String(this) to return? You might try this.text() instead (see API doco: .text()). — RobG
– RobG, Commented Mar 17, 2016 at 22:28
Yes, it was an object first, that's why I did the String(this), so I could do the .match to extract the date — BenjaVR
– BenjaVR, Commented Mar 17, 2016 at 22:30
String(object) will call the object's toString method. I don't think jQuery sets a specific method, so you'll get the built–in Object.prototype.toString , which is probably returning something like [object Object]. — RobG
– RobG, Commented Mar 17, 2016 at 22:32
Also note that if you intend converting "2016-02-10 13:27" to a date, then you'll need to parse it manually (a library can help but it only needs a 2 line function). That format isn't one supported by ECMAScript 2015, so parsing is implementation dependent. Some will treat it as UTC, some as local and the rest as invalid. — RobG
– RobG, Commented Mar 17, 2016 at 22:37
You were right about the [object Object] return! Didn't noticed that... Thanks! I also didn't know about the converting problem, have to check that out, good to know. — BenjaVR
– BenjaVR, Commented Mar 17, 2016 at 22:42

gabesoft · Accepted Answer · 2016-03-17 22:50:03Z

0

You could also try to create a date object. And check whether a valid date was created

var date = new Date($(this).text());
if (isNaN(date.getTime())) {
  // invalid date
} else {
  // valid date
}

edited Mar 17, 2016 at 22:50

answered Mar 17, 2016 at 22:29

gabesoft

1,2289 silver badges6 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

BenjaVR Over a year ago

Works as a charm, thank you! I changed it to (!isNaN(date.getTime())), because I only need the valid dates.

BenjaVR Over a year ago

Oh, and there is a ) missing after (isNaN(date.getTime())

RobG Over a year ago

Please don't recommend parsing strings with the Date constructor, it's unreliable (to say the least).

gabesoft Over a year ago

Thanks @RobG I'll keep that in mind

Collectives™ on Stack Overflow

Javascript extract date from certain elements with match and regex returns empty array [duplicate]

1 Answer 1

4 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Linked

Related