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@effection/effection@3.4.0
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thefrontside/effection

Structured Concurrency and Effects for JavaScript

This package works with Cloudflare Workers, Node.js, Deno, Bun, Browsers
This package works with Cloudflare Workers
This package works with Node.js
This package works with Deno
This package works with Bun
This package works with Browsers
JSR Score
100%
Published
a day ago (3.4.0)
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interface Scope

A programatic API to interact with an Effection scope from outside of an Operation.

Most often this is used to integrate external APIs with Effection by capturing a Scope from a running operation with useScope, and then using it to call back into itself from a callback.

The following example calls into Effection to implement a proxy around a google search by using express.js.

Examples

Example 1

import { main, useScope, suspend } from "effection";
import { express } from "express";

await main(function*() {
  let scope = yield* useScope();
  express().get("/", (req, resp) => {
    return scope.run(function*() {
      let signal = yield* useAbortSignal();
      let response = yield* fetch(`https://google.com?q=${req.params.q}`, { signal });
      resp.send(yield* response.text());
    });
  });
  yield* suspend();
});

Methods

run<T>(operation: () => Operation<T>): Task<T>

Spawn an Operation within Scope.

This is used to create concurrent tasks from outside of a running operation.

get<T>(context: Context<T>): T | undefined

Get a Context value from outside of an operation.

set<T>(
context: Context<T>,
value: T,
): T

Set the value of a Context from outside of an operation

expect<T>(context: Context<T>): T

Get a Context value from outside of an operation, and throw a MissingContextError if this context is not specified for this scope.

delete<T>(context: Context<T>): boolean

Remove a Context value from this scope.

hasOwn<T>(context: Context<T>): boolean

Check if scope has its own unique value for context.

Add Package

deno add jsr:@effection/effection

Import symbol

import { type Scope } from "@effection/effection";

---- OR ----

Import directly with a jsr specifier

import { type Scope } from "jsr:@effection/effection";

Add Package

npx jsr add @effection/effection

Import symbol

import { type Scope } from "@effection/effection";

Add Package

yarn dlx jsr add @effection/effection

Import symbol

import { type Scope } from "@effection/effection";

Add Package

pnpm dlx jsr add @effection/effection

Import symbol

import { type Scope } from "@effection/effection";

Add Package

bunx jsr add @effection/effection

Import symbol

import { type Scope } from "@effection/effection";