feat: add optional params for hash and searchParams to resolve()

[codevogel]

Please go easy on me as this is the first PR I'm making to this repository, I am more than open to any suggested changes. I've been trying to get some help with this PR from the official Discord server, but discussion was pretty stale. So I'm hoping by opening this PR we can get this change going. Or, if the conclusion is 'we shouldnt do this at all', that's fine too!

Adds optional arguments for URL params hash and searchParams to resolve(). Appends these to the returned URL after resolving the path.

Resolves #14750 and helps address sveltejs/eslint-plugin-svelte#1353

• Additionally updates the example docstring to show new usage:

import { resolve } from '$app/paths';

// using a pathname
const resolved = resolve(`/blog/hello-world`);

// using a route ID plus route parameters
const resolved = resolve('/blog/[slug]', {
	slug: 'hello-world'
});

// using a route ID plus URL parameters
const resolved = resolve('/blog/search',
	{ hash: 'results', searchParams: { author: 'John Doe', year: '2025' } }
});

// using a route ID plus route parameters and URL parameters
const resolved = resolve('/blog/[slug]',
	{ slug: 'hello-world' },
	{ hash: 'introduction' }
});

---

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• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
  • PR references an issue, but no discussion as of yet.
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.
  • I tried writing some tests in kit/packages/kit/test/apps/basics/test/client.test.js, but was met with ReferenceError: __SVELTEKIT_PAYLOAD__ is not defined at ../../../../src/runtime/app/paths/internal/client.js:1. This makes sense, because resolveRoute is used in resolve, which uses base, which needs __SVELTEKIT_PAYLOAD__. I wasn't able to find any existing tests for resolve or resolveRoute, other than at packages/kit/test/apps/options/test/test.js at line 97, which seems to be more of an integration test than actually testing resolveRoute itself.
    This is my first PR for this repo, so I'm not sure where below tests should go.
    Willing to add these if I get some pointers in the right direction.

  import { resolve } from '../../../../src/runtime/app/paths/client.js';
  
  describe('resolve function', () => {
     it('resolves a simple pathname', () => {
         const result = resolve('/blog/hello-world');
         expect(result).toBe('/blog/hello-world');
     });
  
     it('resolves a route ID with dynamic parameters', () => {
         const result = resolve('/blog/[slug]', { slug: 'hello-world' });
         expect(result).toBe('/blog/hello-world');
     });
  
     it('resolves a route ID with URL parameters', () => {
         const result = resolve('/blog/search', {
             hash: 'results',
             searchParams: { author: 'John Doe', year: '2025' }
         });
         expect(result).toBe('/blog/search?author=John%20Doe&year=2025#results');
     });
  
     it('resolves a route ID with both dynamic and URL parameters', () => {
         const result = resolve('/blog/[slug]', { slug: 'hello-world' }, { hash: 'introduction' });
         expect(result).toBe('/blog/hello-world#introduction');
     });
  
     it('handles empty parameters gracefully', () => {
         const result = resolve('/blog/[slug]', {});
         expect(result).toBe('/blog/[slug]');
     });
  });

Tests

• Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

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[changeset-bot]

🦋 Changeset detected

Latest commit: 50af08d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@sveltejs/kit	Minor

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-14756-svelte.vercel.app/

[kkarikos]

Came to this PR from suffering from the huge eslint breakage due to this not being possible. 👍

I'd like to see this be at least searchParams?: Record<string, string> | URLSearchParams;.

[codevogel]

That would make sense. Happy to implement that too, I'm just a bit lost as to why the tests are failing.

[codevogel]

@kkarikos I implemented your suggestion!

[codevogel]

Any pointers as to why svelte.dev / preview deployments fails?

When I try to see the details, I just get met with a 404 error in Vercel.