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Comment by luotuoshangdui | Hacker News Reader

HTML is a markup language, not a programming language. It's like asking why Markdown can't handle includes. Some Markdown editors support them (just like some server-side tools do for HTML), but not all.

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Including another document is much closer to a markup operation than a programming operation. We already include styles, scripts, images, videos, fonts...why not document fragments?

Markdown can't do most of those, so it makes more sense why it doesn't have includes, but I'd still argue it definitely should. I generally dislike LaTeX, but about the only thing I liked about it when writing my thesis was that I could have each chapter in its own file and just include all of them in the main file.

This isn’t programming. It’s transclusion[0]. Essentially, iframes and images are already forms of transclusion, so why not transclude html and have the iframe expand to fit the content?

As I wrote that, I realized there could be cumulative layout shift, so that’s an argument against. To avoid that, the browser would have to download all transcluded content before rendering. In the past, this would have been a dealbreaker, but maybe it’s more feasible now with http multiplexing.

[0] https://en.m.wikipedia.org/wiki/Transclusion#Client-side_HTM...

With Early Hints (HTTP code 103), it seems especially feasible. You can start downloading the included content one round-trip after the first byte is sent.

Well, asciidoc - a markup language supports includes, so the "markup languages" analogy doesn't hold.

https://docs.asciidoctor.org/asciidoc/latest/directives/incl...

That’s the Hyper part of HTML, and what makes it special.

It’s made to pull in external resources (as opposed to other document formats like PDF).

Scripts, stylesheets, images, objects, favicons, etc. HTML is thematically similar.

No, HTML is fundamentally different because (for a static site without any JS dom manipulation) it has all the semantic content, while stylesheets, images, objects, etc. are just about presentation.

Iframes exist.

Images are content. Videos are content. Objects/iframes are content.

The only one that is presentational is stylesheets.

Which (as I'm sure you know), also literally has 'content' :)

https://developer.mozilla.org/en-US/docs/Web/CSS/content

True :)

Images and videos are not semantic content. The alt attributes that describe them on the other hand are indeed semantic content.

> Images and videos are not semantic content

Something in that tenet does not compute with me.

I think the distinction is "semantic on what level/perspective?". An image packaged as a binary blob is semantically opaque until it is rendered. Meanwhile, seeing <img> in the HTML or the file extension .jpg in any context that displays file extensions tells me some information right out of the gate. And note that all three of these examples are different information: the HTML tag tells me it's an image, whereas the file extension tells me it's a JPEG image, and the image tells me what the image contains. HTML is an example of some kind of separation, as it can tell you some semantic meaning of the data without telling you all of it. Distinguishing and then actually separating semantics means data can be interpreted with different semantics, and we usually choose to focus on one alternative interpretation. Then I can say that HTML alone regards some semantics (e.g. there is an image here) while disregarding others (e.g. the image is an image of a brick house).

I'm not sure what isn't computing. Presumably you know (or have looked up) the meaning of "semantic"? Images and videos are graphic, not semantic, content. To the extent they are rendering semantic content, that content should be described in the alt tag.

Can you describe what semantic, non-textual content would be?

I think this is the most likely answer.

I'm not defending it, because when I started web development this was one of the first problems I ran into as well -- how the heck do you include a common header.

But the original concept of HTML was standalone documents, not websites with reusable components like headers and footers and navbars.

That being said, I still don't understand why then the frames monstrosity was invented, rather than a basic include. To save on bandwidth or something?

A lot of early HTML was about taking the output of a different system such as a mainframe and putting that output into HTML.

Lots of gateways between systems.

Frames were widely abused by early web apps to do dynamic interfaces before XHR was invented/widely supported. The "app" had a bunch of sub-frames with all the links and forms carefully pointing to different frames in the frameset.

A link in a sidebar frame would open a link in the "editor" frame which loaded a page with a normal HTML form. Submitting the form reloaded it in that same frame. Often the form would have multiple submit buttons, one to save edits in progress and another to submit the completed form and move to the next step. The current app state was maintained server side and validation was often handled there save for some basic formatting client side JavaScript could handle.

This setup allowed even the most primitive frame-supporting browsers to use CRUD web apps. IIRC early web frameworks like WebObjects leaned into that model of web app.

Oh my goodness, yes you're right, I'd forgotten entirely about those.

They were horrible -- you'd hit the back button and only one of the frames would go back and then the app would be in an inconsistent state... it was a mess!

You needed to hit the reset button (and hoped it worked) and never the back button! Yes, I suffered through early SAP web apps built entirely with frames and HTML forms. It was terrible.

I don't love JavaScript monstrosities but XHR and dynamic HTML were a vast improvement over HTML forms and frame/iframe abuse.

To be fair, modern SAP web apps are also terrible.

Really well written web form applications were a delight in 2001 and a large improvement over conventional applications written in Windows. It helped that application data was in a SQL database, with a schema, protected by transactions, etc as opposed to a tangle of pointers that would eventually go bad and crash the app -- I made very complicated forms for demographic profiling, scientific paper submission, application submission, document search, etc. If you did not use "session" variables for application state this could at worst cause a desynchronization between the browser and the server which (1) would get resynchronized at any load or reload and (2) never get the system into a "stuck" state from the user viewpoint and (3) never lose more than a screen full of work.

Try some other architecture though and all bets were off.

Amazon's web store looked and worked mostly the same as it does now, people were very impressed with MapQuest, etc.

Applications like that can feel really fast, almost desktop application fast, if you are running them on a powerful desktop computer and viewing them on another computer or tablet over a LAN

The original concept of HTML was as an SGML subset, and SGML had this functionality, precisely because it's very handy for document authoring to be able to share common snippets.

Markdown doesn't have this common HTML pattern of wanting to include a header/footer in all pages of a site.

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