this post was submitted on 20 May 2024
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Web Development

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Is it possible to get the value of a CSS property in an HTML element, using XPath 1.0? (sh.itjust.works)
submitted 5 months ago by [email protected] to c/webdev
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Say you have HTML similar to the following:

<div style="background-image: url('https://some.domain/image')"></div>

and you want to extract https://some.domain/image using XPath. With XPath 2.0, you can select the URL with something like

select-before(select-after(//div/@style, "backgound-image: url("), ")")

but, when using XPath 1.0, this fails — I think it's due to nested functions not being supported in XPath 1.0, but I have been unable to find documentation to confirm that. Is there a way to accomplish this using XPath 1.0?

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[–] towerful 2 points 5 months ago* (last edited 5 months ago)

A quick Google suggests what you have.

If the code you have quoted is verbatim what you have tried, seems like you need to extract the parentheses and possibly a single or double quote, depending on the source css. The example source you have given has a single quote.

select-before(select-after(//div/@style, "backgound-image: url("), ")")

Should be (notice the extra ' relating to url('...url'))

select-before(select-after(//div/@style, "backgound-image: url('"), "')")

But I don't think that would cause xpath to fail... It would just extract the wrong value

Edit:
Further reading suggests xpath 1.0 does have limited functionalities. But, like you, can't find anything concrete.

[–] spartanatreyu 1 points 5 months ago (1 children)

Asking just because I'm curious... why are you using xpath?

Also, is this for a website you control or for some else's website?

If you're rendering the page (in a browser, e2e test-runner, spider bot, etc...), have you considered running some js on the page to get the image? Something like: const imagePath = document.getElementById('exampleIdOnElement').style.backgroundImage

[–] [email protected] 1 points 5 months ago* (last edited 5 months ago)

Asking just because I’m curious… why are you using xpath?

I'm using a service called FreshRSS that automatically fetches RSS feeds. It has a feature that allows you to create custom feeds for sites by scraping the HTML with user specified XPath expressions.

I know that this isn't exactly "web development", but it uses webdev tools, and I wasn't entirely sure where else to post this.

If you’re rendering the page (in a browser, e2e test-runner, spider bot, etc…), have you considered running some js on the page to get the image? Something like: const imagePath = document.getElementById('exampleIdOnElement').style.backgroundImage

JS is, unfortunately, not possible here. I can only use XPath expressions.