svelte-qparam

// extract.js
import { array, define } from 'svelte-qparam'
import { boolean, number, string } from 'svelte-qparam/serde'

export const extract = define({
  str: string,
  num: number,
  bool_array: array(boolean)
})

// +page.server.js
import { extract } from 'extract.js'

export const load = ({ url }) => {
  const { values } = extract(url)

  /* {
    str: string;
    num: number;
    bool_array: boolean[];
  } */
  console.log(values)

  return {
    values
    // Note: Cannot return `qparams` from server
    // ...
  }
}

<!-- +page.svelte -->
<script>
  let { data } = $props()

  let { values } = $derived(data)
  let { str, num, bool_array } = $derived(values)
</script>

<output>
  <code>server_str = {str}</code>
  <code>server_num = {num}</code>
  <code>server_bool_array = {JSON.stringify(bool_array)}</code>
</output>