zustand-querystring

A Zustand middleware that syncs the store with the querystring.

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Examples:

• React
• NextJS

Quickstart:

import create from 'zustand';
import { querystring } from 'zustand-querystring';

interface Store {
  count: number;
  ticks: number;
  someNestedState: {
    nestedCount: number;
    hello: string;
  };
}

export const useStore = create<Store>()(
  querystring(
    (set, get) => ({
      count: 0,
      ticks: 0,
      someNestedState: {
        nestedCount: 0,
        hello: 'Hello',
      },
    }),
    {
      // select controls what part of the state is synced with the query string
      // pathname is the current route (e.g. /about or /)
      select(pathname) {
        return {
          count: true,
          // ticks: false, <- false by default

          someNestedState: {
            nestedCount: true,
            hello: '/about' === pathname,
          },

          // OR select the whole nested state
          // someNestedState: true
        };
      },
    },
  ),
);

querystring options:

• select - the select option controls what part of the state is synced with the query string
• key: string - the key option controls how the state is stored in the querystring (default: 'state')
• url - the url option is used to provide the request url on the server side render
• format - custom format for stringify/parse (default: JSON-based format)
• syncNull: boolean - when true, null values that differ from initial state are synced to URL (default: false)
• syncUndefined: boolean - when true, undefined values that differ from initial state are synced to URL (default: false)

Important Notes

State Diffing

Only values that differ from the initial state are synced to the URL.

Null and Undefined Handling

By default (syncNull: false, syncUndefined: false), null and undefined values are not synced to the URL. This means setting a value to null or undefined effectively "clears" it back to the initial state on page refresh.

If you want to preserve null or undefined values in the URL (so they persist across refreshes), set syncNull: true or syncUndefined: true in options.

State Types

• Plain objects (created with {}) are recursively compared with initial state - only changed properties are synced
• Arrays, Dates, RegExp, Maps, Sets, and class instances are compared as atomic values - if any part changes, the entire value is synced
• Functions are never synced to the URL