use-cookie-state

A simple, yet flexible React hook for managing persistent state through browser cookies.
By leveraging browser cookies, use-cookie-state ensures that your component states remain consistent and available even after a page reload. It gracefully handles both client and server-side rendering (SSR) scenarios.

Key Highlights:
- Persistent state: Store your React state in browser cookies.
- Similar to useState: Familiar API and usage, making it intuitive for React developers.
- Flexible options: Customizable cookie settings, including maxAge, expires, domain, path, secure, httpOnly, sameSite, priority, and partitioned.
- SSR-friendly: Falls back to useState behavior when document.cookie is not accessible.


Table of Contents

- use-cookie-state
- Table of Contents
- Installation
- API Reference
- Cookie Options
- Default Encode Options:
- Other Encode Options:
- Examples
- Basic Usage
- Handling Complex Data (JSON)
- Custom Cookie Settings
- Runtime Overrides
- Server-Side Rendering (SSR)
- Tips \& Best Practices
- License

---

Installation

Using npm:
``bash
npm install --save use-cookie-state cookie
`

Using yarn:
`bash
yarn add use-cookie-state cookie
`

> Note: The cookie package is a peer dependency and must be installed alongside use-cookie-state.

---

API Reference

`ts
useCookieState(
key: string,
initialValue: T,
options?: {
decode?: (value: string) => any;
encode?: CookieSerializeOptions;
}
): [T, (value: T, encode?: CookieSerializeOptions) => void];
`

Parameters:
- key (string, required): Cookie name.
- initialValue (T, required): Initial state value. Can be a primitive, object, or a function returning the initial value.
- options (optional):
- decode: A function to decode the cookie value when reading it from document.cookie.
- encode: An object specifying default cookie attributes used when writing the cookie.

!IMPORTANT!: Due the cookie package implementation, the decode function will be applied for each cookie value, during the cookies parsing process. Be patient to use try/catch block to avoid errors.

Return Value:
- An array [value, setValue] similar to useState:
- value: The current state derived from the cookie.
- setValue(value: T, encode?: CookieSerializeOptions): Updates the cookie (and the state). Accepts optional runtime encode options to override defaults.

---

Cookie Options

When setting or updating cookies, you can specify cookie-related attributes as encode options. These options influence how the cookie is stored and retrieved by the browser. All cookie attributes are optional.

$3

- maxAge (number): Maximum age of the cookie in seconds. If both expires and maxAge are set, maxAge takes precedence.
- expires (Date): Specific date and time when the cookie should expire.
- domain (string): The domain for which the cookie is valid. Defaults to the current domain if not set.
- path (string): The path for which the cookie is valid. Defaults to "/".
- httpOnly (boolean): If true, the cookie is not accessible to client-side JavaScript.
- secure (boolean): If true, the cookie is only sent over HTTPS connections.
- sameSite (true | "strict" | "lax" | "none"): Controls cross-site request behavior.
- true or "strict": Strict same-site enforcement.
- "lax": Lax same-site enforcement.
- "none": No same-site restrictions.
- priority ("low" | "medium" | "high"): Sets the cookie’s priority.
- partitioned (boolean): Enables the Partitioned attribute for the cookie (experimental).

> You can find more details about these options in the cookie package documentation: CookieSerializeOptions.

---

Examples

$3

`jsx
import React from "react";
import { useCookieState } from "use-cookie-state";

function MyComponent() {
const [value, setValue] = useCookieState("username", "JohnDoe");

return (


export default MyComponent;
`

$3

For objects/arrays, store as JSON and provide a decode function:

`jsx
import React from "react";
import { useCookieState } from "use-cookie-state";

function jsonDecode(value) {
try {
return JSON.parse(value);
} catch {
return value;
}
}

function MyComponent() {
const [data, setData] = useCookieState("myData", { foo: "bar" }, { decode: jsonDecode });

const updateData = () => {
setData({ foo: "baz", count: 1 });
};

return (


{JSON.stringify(data, null, 2)}

export default MyComponent;
`

!IMPORTANT!: Due the cookie package implementation, the decode function will be applied for each cookie value, during the cookies parsing process. Be patient to use try/catch block to avoid errors.

$3

`jsx
import React from "react";
import { useCookieState } from "use-cookie-state";

function MyComponent() {
const [value] = useCookieState("myKey", "initialVal", {
encode: {
maxAge: 60 60 24 * 7, // 1 week
secure: true,
sameSite: "strict",
httpOnly: true
}
});

return

export default MyComponent;
`

$3

`jsx
import React from "react";
import { useCookieState } from "use-cookie-state";

function MyComponent() {
const [state, setState] = useCookieState("userToken", "abc123", {
encode: { secure: true, path: "/" }
});

const updateToken = () => {
// Add domain at runtime, merging it with the default secure and path options
setState("newTokenValue", { domain: "example.com" });
};

return (


export default MyComponent;
`

---

Server-Side Rendering (SSR)

On the server, document.cookie is not available. During SSR:
- useCookieState uses the provided initialValue directly, just like useState.
- No cookie operations occur until the browser environment is available.

Once hydrated, it will sync the component state with any browser cookies.

---

Tips & Best Practices

1. Keep cookie size small: Most cookies have size limits (~4KB).
2. Use JSON for complex data: Consider JSON.stringify on write and a custom decode function on read.
3. Security considerations: Use secure: true if your site uses HTTPS.
4. Domain and path: Control where cookies are valid with domain and path.
5. SameSite attribute: Consider sameSite` to protect against CSRF attacks or to allow cross-site requests depending on your needs.

---

License

MIT © dqunbp