as-fetch

library2.1.4jsnpmunverified

A fetch API implementation for AssemblyScript (WebAssembly) that supports both asynchronous and synchronous HTTP requests. Current stable version is 2.1.4, with periodic releases. Key differentiators: fully typed for AssemblyScript, offers optional synchronous mode via transform, and provides both raw and ESM bindings for host integration. Unlike JavaScript fetch, it requires explicit binding setup and response handler exports. Suitable for AssemblyScript projects needing HTTP client functionality in WebAssembly.

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npm install as-fetch

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INSTALL

IMPORT

SIG · AS-FETCH

as-fetch

devopsjavascriptv2.1.4

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

fetch

✓ import { fetch } from 'as-fetch/assembly';

✗ import { fetch } from 'as-fetch';

The main fetch function is exported from the 'assembly' subpath; the top-level package does not expose fetch directly.

fetchSync

✓ import { fetchSync } from 'as-fetch/sync';

✗ import { fetchSync } from 'as-fetch/assembly';

Synchronous fetch is in a separate subpath 'as-fetch/sync'. Use this only when the synchronous transform is applied.

responseHandler

✓ export { responseHandler } from 'as-fetch/assembly';

✗ import { responseHandler } from 'as-fetch/assembly';

For async fetch, responseHandler must be re-exported from your AssemblyScript module, not imported. It is consumed by the host bindings.

FetchHandler

✓ import { FetchHandler } from 'as-fetch/bindings.raw.esm.js';

✗ import { FetchHandler } from 'as-fetch';

FetchHandler is a JavaScript class from the raw ESM bindings, not available in AssemblyScript imports.

Demonstrates async fetch in AssemblyScript with response handler export and basic usage.

// AssemblyScript file (e.g., index.ts) import { fetch } from "as-fetch/assembly"; export { responseHandler } from "as-fetch/assembly"; export function main(): void { fetch("https://api.example.com/data", { method: "GET", mode: "no-cors", headers: [], body: null, }).then((response) => { const body = response.text(); console.log("Status: " + response.status.toString()); console.log("Body: " + body); }); }

Debug

Known issues

gotchaAsync fetch requires exporting 'responseHandler' from the assembly module; omitting it causes runtime errors.

fix

Add 'export { responseHandler } from 'as-fetch/assembly';' to your module.

affects: >=0.0.0

gotchaSynchronous fetch requires the 'as-fetch/transform' transform to be applied to the asc compiler; otherwise fetchSync will not work.

fix

Add '--transform as-fetch/transform' to asc command or configure in asconfig.json.

affects: >=0.0.0

gotchaThe FetchHandler class must be instantiated with a fetch function (e.g., global fetch) before use; supplying undefined causes bindings to fail.

fix

Ensure fetch is available in the host environment (Node, browser) and pass it to FetchHandler: new FetchHandler(fetch).

affects: >=0.0.0

Errors

Common errors & fixes

Error: responseHandler is not defined or not exported

The AssemblyScript module did not export responseHandler as required by async fetch.

fix

Add 'export { responseHandler } from 'as-fetch/assembly';' to your AssemblyScript entry file.

TypeError: fetchSync is not a function

The synchronous transform was not applied or fetchSync was imported from wrong path.

fix

Ensure you use '--transform as-fetch/transform' in asc command and import fetchSync from 'as-fetch/sync'.

Error: FetchHandler.imports is not an object or undefined

FetchHandler was not instantiated correctly or missing new keyword.

fix

Use 'const Fetch = new FetchHandler(fetch);' and verify fetch is defined.

Upgrade

Version history

2.1.4latest on npm

Audit

Dependencies

assemblyscriptoptionalRuntime dependency for AssemblyScript compilation and execution

Agent activity

17 hits · last 30 days

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Resources

githubhttps://github.com/JairusSW/as-fetch ↗

packageas-fetch ↗

homepagehttps://github.com/JairusSW/as-fetch#readme ↗