Why script-tags are placed at the bottom of the page in Prosilver?

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Sectoid
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Why script-tags are placed at the bottom of the page in Prosilver?

Post by Sectoid » Wed Sep 13, 2017 2:50 pm

In Prosilver, script-tags are placed at the bottom of the page. This allows static content of the page to be shown a little bit faster to a user who doesn't have necessary resources yet in his browser cache. On some sites, this may be beneficial. For example, if the site has mostly random users who are not loading several pages during a visit.

But are there any other advantages?

The major drawback is that the DOM cannot be modified until it has been loaded completely. If you need to modify DOM but can't do it until the ONLOAD event, the page may flicker, element positions may change etc. This is annoying and confusing to a user.

A forum is usually such a website where most visitors are returning users who have all the resources already in browser cache most of the time. Therefore, I'm suggesting that the scripts, especially jQuery, would be loaded in the head-tag.

PS. 504, 504, 504...

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hanakin
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Re: Why script-tags are placed at the bottom of the page in Prosilver?

Post by hanakin » Wed Sep 13, 2017 4:40 pm

It's done was done to also account for async. Not to mention most of the js has to wait. If there is js that does not then it can be placed in the header but this is a case by case basis. The real issue is that the js needs completely rewritten modularly and packaged into header/footer files but that is a massive undertaking. One that would be best held for the new theme and not something that will happen for prosilver most likely except retroactively. However your example is flawed as jquery should always be in the footer as it implicitly requires the son to be built. This is a standard practice

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Re: Why script-tags are placed at the bottom of the page in Prosilver?

Post by Sectoid » Wed Sep 13, 2017 6:39 pm

Thanks for the explanation.
hanakin wrote:
Wed Sep 13, 2017 4:40 pm
jquery should always be in the footer as it implicitly requires the son to be built. This is a standard practice
I don't understand this. Son? Standard? Are you talking about jQuery in general or jQuery in phpBB? In my knowledge there's no requirements about where to put the jQuery.

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Re: Why script-tags are placed at the bottom of the page in Prosilver?

Post by hanakin » Wed Sep 13, 2017 8:38 pm

Son was an autocorrect apologies I meant dom. As far as a standard yes it requires the dom to be ready that is what document.ready means

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Re: Why script-tags are placed at the bottom of the page in Prosilver?

Post by Sectoid » Wed Sep 13, 2017 9:41 pm

hanakin wrote:
Wed Sep 13, 2017 8:38 pm
As far as a standard yes it requires the dom to be ready that is what document.ready means
I don't buy this. Only difference between script tags in <head> and <body> is the amount of markup above the script tag, right?

Even if the script tag for jQuery is at the bottom of the page there's still at least </body> and </html> tags below it. You can start manipulating the unfinished DOM if the browser supports it but the DOM is definitely not ready at that point. So, in any case (scripts in <head> or <body>), you should use listeners to test if the DOM is ready. And when you start doing that, it does not matter where to put the script tag.

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Re: Why script-tags are placed at the bottom of the page in Prosilver?

Post by DavidIQ » Wed Sep 13, 2017 9:56 pm

I echo the comment already mentioned: loading jQuery near the bottom of pages is fairly standard practice and isn't anything new.
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Re: Why script-tags are placed at the bottom of the page in Prosilver?

Post by Sectoid » Wed Sep 13, 2017 10:14 pm

DavidIQ wrote:
Wed Sep 13, 2017 9:56 pm
I echo the comment already mentioned: loading jQuery near the bottom of pages is fairly standard practice and isn't anything new.
I'm not sure do we have some kind of a language barrier here but to me "standard" sounds like "this is how it should be done".

I agree many sites put jQuery at the end but disagree it should be there always. Even https://jquery.com/ loads jQuery in <head>!

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Re: Why script-tags are placed at the bottom of the page in Prosilver?

Post by DavidIQ » Wed Sep 13, 2017 10:20 pm

Ok then let me go a different route you can maybe understand better: exactly what in phpBB flickers when loading that is caused by jQuery being near the bottom of the page?
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Re: Why script-tags are placed at the bottom of the page in Prosilver?

Post by Sectoid » Wed Sep 13, 2017 10:39 pm

DavidIQ wrote:
Wed Sep 13, 2017 10:20 pm
Ok then let me go a different route you can maybe understand better: exactly what in phpBB flickers when loading that is caused by jQuery being near the bottom of the page?
If, for example, I want to made an extension that automatically shows a mobile version of the page or changes the width of the page or something like that... The only way to do that without user seeing unnecessary flickering and element re-sizing is to manipulate the DOM as early as possible.

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Re: Why script-tags are placed at the bottom of the page in Prosilver?

Post by DavidIQ » Wed Sep 13, 2017 10:56 pm

So you haven't actually run into this issue developing an extension or doing something with phpBB?

The way jQuery is loaded in prosilver has not changed in over 6 years, that's pre-3.1.0-Alpha. The pros and the cons were weighed here:
viewtopic.php?f=84&t=41199
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