Please explain the legitimate uses. Not once I have ever encountered a website that does something useful by modifying the behavior of my browsing history.

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least 9 hours ago | parent | next [-]

https://html.spec.whatwg.org/multipage/nav-history-apis.html...

The spec kind of goes into it, but aside from the whole SPAs needing to behave like individual static documents, the big thing is that it's a place to store state. Some of this can be preserved through form actions and anchor tags but some cannot.

Let's say you are on an ecommerce website. It has a page for a shirt you're interested in. That shirt has different variations - color, size, sleeve length, etc.

If you use input elements and a form action, you can save the state that way, and the server redirects the user to the same page but with additional form attributes in the url. You now have a link to that specific variation for you to copy and send to your friend.

Would anyone really ever do that? probably not. More than likely there'd just be an add to cart button. This is serviceable but it's not necessarily great UX.

With the History API you can replace the url with one that will embed the state of the shirt so that when you link it to your friend it is exactly the one you want. Or if you bookmark it to come back to later you can. Or you can bookmark multiple variations without having to interact with the server at all.

Similarly on that web page, you have an image gallery for the shirt. Without History API, maybe You click on a thumbnail and it opens a preview which is a round trip to the server and a hard reload. Then you click next. same thing. new image. then again. and again. and each time you are adding a new item to the history stack. that might be fine or even preferred, but not always! If I want to get back to my shirt, I now have to navigate back several pages because each image has been added to the stack.

If you use the History API, you can add a new url to the stack when you open the image viewer. then as you navigate it, it updates it to point to the specific image, which gives the user the ability to link to that specific image in the gallery. when you're done. If you want to go back you only have to press back once because we weren't polluting the stack with history state with each image change.

	▲	jack1243star 9 hours ago \| parent [-]
		Thanks for the detailed and thoughtful reply! I agree that in both of the scenarios you mentioned, this API does provide better usability. I guess what feels wrong to me is the implicitness of this feature, I'm not sure whether clicking on something is going to add to history or not (until the back button breaks, then I really know).

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venussnatch 11 hours ago | parent | prev [-]

Any single page application, such as YouTube, Gmail, or discord.

It lets persistent content (videos) or connections (chat) persist while emulating a pagenated browsing experience.

When it's done right you don't notice it at all.

	▲	mrob 8 hours ago \| parent \| next [-]
		Youtube doesn't implement a back function. A real back function would take you back to the same page you came from. If you click a video from the Youtube home page, then click the back button, Youtube will regenerate a different home page with different recommendations, losing the potentially interesting set of recommendations you saw before. You are forced to open every link in a new tab if you want true back functionality.
	▲	jack1243star 10 hours ago \| parent \| prev [-]
		(rant warning) Well, if I wanted to return to the parent screen in a single page application, I'd click on the back button in the app itself. No need to prevent me from back tracking in the exact order of my browsing should I need it. I especially hate YouTube's implementation, I can never know the true state on my older PC during whatever it's trying to accomplish, often playing audio from a previous video when I backspace out. I resort to opening every link in a new tab.