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https://github.com/maxgfr/node-simple-context
A minimalist context for node, inspired by React Context API
https://github.com/maxgfr/node-simple-context
async-hooks async-local-storage context context-api global-variables node-context promise typescript
Last synced: 7 days ago
JSON representation
A minimalist context for node, inspired by React Context API
- Host: GitHub
- URL: https://github.com/maxgfr/node-simple-context
- Owner: maxgfr
- License: mit
- Created: 2022-04-29T17:57:17.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2024-10-29T23:13:32.000Z (15 days ago)
- Last Synced: 2024-10-30T01:48:42.940Z (14 days ago)
- Topics: async-hooks, async-local-storage, context, context-api, global-variables, node-context, promise, typescript
- Language: TypeScript
- Homepage: https://www.npmjs.com/package/node-simple-context
- Size: 1.76 MB
- Stars: 1
- Watchers: 2
- Forks: 1
- Open Issues: 7
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# node-simple-context
`node-simple-context` is an helper to create a context in node.
This library is highly inspired by [nctx](https://github.com/devthejo/nctx). You definitely should check it out! Thanks to [@devthejo](https://github.com/devthejo) for his help 💪
## Installation
```sh
npm install node-simple-context
```
## Usage
### Simple example
#### 1. Create a new file `my-context.ts` in which you define your context.
```ts
import { createSimpleContext } from 'node-simple-context';
export const contextA = createSimpleContext();
export const contextB = createSimpleContext();
```
#### 2. You now can set the context in your code wherever you want
```ts
import { contextA, contextB } from './my-context';
contextA.set('foo', 'bar');
contextB.set('foo', 'baz');
```
#### 3. And, get your context value wherever you want
```ts
import { contextA, contextB } from './my-context';
console.log(contextA.get('foo')); // bar
console.log(contextB.get('foo')); // baz
console.log(contextA.get('xxx')); // undefined
// in typescript
console.log(contextA.get('foo')); // bar
```
### Complex examples
#### By forking your context
Thanks to [`AsyncLocalStorage`](https://nodejs.org/api/async_context.html) api, you can `fork` your context in promise or async functions. As you can see below:
> You can also pass a callback in `fork` method to runs a function synchronously within a context and returns its return value which uses [run method from AsyncLocalStorage](https://nodejs.org/api/async_context.html#asynclocalstoragerunstore-callback-args) (cf. [example](./src/__tests__/context.test.ts#L134))
```ts
const context = createSimpleContext();
const func = (): string => {
const foo = context.get('foo');
return `foo=${foo}`;
};
context.fork();
context.set('foo', 'bar');
const res = await Promise.all([
new Promise((resolve) => {
context.fork().set('foo', 'tata');
setTimeout(() => {
resolve(func());
}, 400);
}),
new Promise((resolve) => {
context.fork().set('foo', 'toto');
setTimeout(() => {
resolve(func());
}, 200);
}),
new Promise((resolve) => {
context.fork().set('foo', 'titi');
setTimeout(() => {
resolve(func());
}, 100);
}),
new Promise((resolve) => {
context.fork().set('foo', 'tutu');
setTimeout(() => {
resolve(func());
}, 600);
}),
]);
console.log(res); // ['foo=tata', 'foo=toto', 'foo=titi', 'foo=tutu']
```
#### By using multiple contexts
```ts
const contextA = createSimpleContext();
const contextB = createSimpleContext();
const contextC = createSimpleContext();
const contextD = createSimpleContext();
const func = (context: SimpleContext): string => {
const foo = context.get('foo');
return `foo=${foo}`;
};
const res = await Promise.all([
new Promise((resolve) => {
contextA.set('foo', 'tata');
setTimeout(() => {
resolve(func(contextA));
}, 400);
}),
new Promise((resolve) => {
contextB.set('foo', 'toto');
setTimeout(() => {
resolve(func(contextB));
}, 200);
}),
new Promise((resolve) => {
contextC.set('foo', 'titi');
setTimeout(() => {
resolve(func(contextC));
}, 100);
}),
new Promise((resolve) => {
contextD.set('foo', 'tutu');
setTimeout(() => {
resolve(func(contextD));
}, 600);
}),
]);
console.log(res); // ['foo=tata', 'foo=toto', 'foo=titi', 'foo=tutu']
```
#### By using multiple keys
```ts
const context = createSimpleContext();
const func = (key: string): string => {
const foo = context.get(key);
return `foo=${foo}`;
};
const res = await Promise.all([
new Promise((resolve) => {
context.set('foo1', 'tata');
setTimeout(() => {
resolve(func('foo1'));
}, 400);
}),
new Promise((resolve) => {
context.set('foo2', 'toto');
setTimeout(() => {
resolve(func('foo2'));
}, 200);
}),
new Promise((resolve) => {
context.set('foo3', 'titi');
setTimeout(() => {
resolve(func('foo3'));
}, 100);
}),
new Promise((resolve) => {
context.set('foo4', 'tutu');
setTimeout(() => {
resolve(func('foo4'));
}, 600);
}),
]);
console.log(res); // ['foo=tata', 'foo=toto', 'foo=titi', 'foo=tutu']
```