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Mohamad Harith
Mohamad Harith

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Mutating Query Params in SvelteKit Without Page Reloads or Navigations

This article assumes the reader understands the basics of SvelteKit framework.

SvelteKit is a rather new framework for building server-side rendered websites. Because it is new, some of the early adopters of the framework were confused on certain usages of the framework. One such confusion was on the usage of query params as seen in these issues: #2785, #969, #2811 - many people, including myself were confused on how to mutate query params of a page without page reloads or navigations.

Some of us thought mutating the params property of $page store would mutate the query params. But this wasn't the cause because the $page store was a read-only store.

Since SvelteKit does not provide a way to mutate the query params, my HOD and I figured that we use the History API's replace state to mutate the query params.

The function:

export const replaceStateWithQuery = (values: Record<string, string>) => {
  const url = new URL(window.location.toString());
  for (let [k, v] of Object.entries(values)) {
    if (!!v) {
      url.searchParams.set(encodeURIComponent(k), encodeURIComponent(v));
    } else {
      url.searchParams.delete(k);
    }
  }
  history.replaceState({}, '', url);
};
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The usage:

  onMount(() => {
    // adds ?foo=bar&john=doe query params to the URL
    replaceStateWithQuery({
      foo: 'bar',
      john: 'doe',
    });
  });
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The replaceStateWithQuery is a function that receives an object of query params and uses the History API's to set these values as the query params of the page. Both the keys and values of the query params will be URL encoded by default. If the value of a query param is null or undefined, the query will be deleted from the URL.

Top comments (11)

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raz0229 profile image
RAZ0229

This is it. Can't believe i spend hours finding other solutions

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codinghusi profile image
Gerrit Weiermann

Thanks for sharing!
I have two improvements:

  1. url.searchParams.set does encodeURLComponent internally so you can remove it
  2. I figured out that you need to pass history.state to the replaceState function. Otherwise routing will break:
export const replaceStateWithQuery = (values: Record<string, string>) => {
  const url = new URL(window.location.toString());
  for (let [k, v] of Object.entries(values)) {
    if (!!v) {
      url.searchParams.set(k, v);
    } else {
      url.searchParams.delete(k);
    }
  }
  history.replaceState(history.state, '', url);
};
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pptavozl profile image
Gustavo Zimbrón

Useful! Thank you!

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spudunk profile image
Christopher Hicks

In my case I only have one set of params so I just ditched the function and used this:

$page.url.searchParams.set(k, v);
history.replaceState(history.state, '', $page.url);
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askrodney profile image
Rodney Lab

Neat, and welcome to dev.to! Any exciting SvelteKit project you're working on right now?

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spudunk profile image
Christopher Hicks

Thanks! And yeah, this problem was applied to Eagans Diner Website for the Ethel location menu tab query

Also been learning a lot on Walking CJ Ranch Website. Some fun image optimization in there using Unpic and Cloudinary.

code for both is in my repo spudunk

What are you working on?

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askrodney profile image
Rodney Lab

Nice, had a scan through your GitHub, hope you're getting paid what you deserve for all this work!

Been looking at using SvelteKit with Tauri to create desktop apps myself, combining Svelte with Rust. Enjoying the experience so far!

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spudunk profile image
Christopher Hicks

Svelte + Rust seems like a powerful combo! If I get into desktop app territory I'll try that route.
Getting paid what it's worth is still a goal!

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dangelomedinag profile image
dangelo

this is amazing. when you travel to the same page through a link, the client side router removes the replaced query parameters from 'onMount' and it is understandable, since the component is not mounted again. So keep that in mind.

thanks for the post.

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chrisjayden profile image
MultipleHats

Maybe it's me, but I think you forgot the add undefined to the Record value as well.

export const replaceStateWithQuery = (values: Record<string, string | undefined>) => {
     ....
};
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fromaline profile image
Nick

Thanks a lot! I spent a couple hours finding the right solution. Yours is great!