`router.resolve` did not handle `<base>` correctly

[ichaoX]

Version

3.6.5

Reproduction link

5s3iuf.csb.app/root/main.html

Steps to reproduce

Click on Link A or open Link B in a new tab.

And check the generated href attribute in the inspector.

What is expected?

In hash mode, the following results are logical, I would prefer the last one, because the HashHistory is not related to the baseURI and the availability of the <base> source is unknown.

// "https://example.com/root/rel/path#/bar"
new URL("#/bar",document.baseURI).href

// "https://example.com/root/main.html#/bar"
new URL("#/bar",location).href
// If location.href and document.baseURI are same-origin or both paths are the same, 
// it is possible to slice the generated URL to shorten it.

What is actually happening?

The generated href attributes are all "/./rel/path#/foo/#/bar".

Both the relative path and the hash of Link A are not handled correctly.

Link B has the same issue when opened in a new tab.

[posva]

A base should likely not include a hash in it. Note that it changes the browser behavior of <a> and other things (https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base). For instance, when you are opening in a new tab, that's the browser, vue-router simply lets that event happen

[ichaoX]

A base should likely not include a hash in it. [citation needed]

I have tested document.baseURI and it will contain the hash value.

Another main problem is that router.resolve treats it as an absolute path, while <base> is a relative path.

It's less reliable here:

vue-router/src/history/base.js

Lines 270 to 288 in 492bf0e

	function normalizeBase (base: ?string): string {
	if (!base) {
	if (inBrowser) {
	// respect <base> tag
	const baseEl = document.querySelector('base')
	base = (baseEl && baseEl.getAttribute('href')) || '/'
	// strip full URL origin
	base = base.replace(/^https?:\/\/[^\/]+/, '')
	} else {
	base = '/'
	}
	}
	// make sure there's the starting slash
	if (base.charAt(0) !== '/') {
	base = '/' + base
	}
	// remove trailing slash
	return base.replace(/\/$/, '')
	}

The hash mode should not join the '/' in the middle, the server may return 404 Not Found.

vue-router/src/router.js

Lines 280 to 283 in 492bf0e

	function createHref (base: string, fullPath: string, mode) {
	var path = mode === 'hash' ? '#' + fullPath : fullPath
	return base ? cleanPath(base + '/' + path) : path
	}

To solve the problem of inconsistent opening in new tabs in hash mode, it can either do nothing special for <base>, or use new URL("#/bar",location).href to generate the URL.