fast-async

library1.1.0jsnpmunverified

A Babel plugin that transforms ES7 async/await to Promise-based code without generators, offering 3-4x performance improvement in browsers vs Babel's default regenerator approach. Current stable version is 6.3.8 (for Babel 6) and version 7 for Babel 7 (beta). Uses the nodent library under the hood. Key differentiators: avoids generators and regenerator, supports 'spec' mode for spec-compliance, and allows runtime pattern customization. Has undergone several fixes for edge cases like destructuring and export hoisting.

serialization

npm install fast-async

github ↗package ↗

INSTALL

IMPORT

SIG · FAST-ASYNC

fast-async

serializationjavascriptv1.1.0

Install

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Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

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

default

✓ module.exports = require('fast-async')

✗ import fastAsync from 'fast-async'

CommonJS only; no default ES import provided. Use require or dynamic import.

Shows basic babel plugin configuration and the transformation from async/await to Promises.

// .babelrc { "plugins": ["fast-async"] } // Input async function fetchData(url) { const response = await fetch(url); return response.json(); } // Output (simplified) function fetchData(url) { return Promise.resolve().then(function() { return fetch(url); }).then(function(response) { return response.json(); }); }

Debug

Known issues

breakingBabel 7 requires 'module:fast-async' plugin prefix instead of 'fast-async'

fix

Use 'module:fast-async' in plugins array for Babel 7.

affects: >=7.0.0

breakingOptions 'augmentObject', 'dontMapStackTraces', 'dontInstallRequireHook' removed in v6.3.x

fix

Remove these options from configuration; they are no longer supported.

affects: >=6.3.0

deprecatedCompiled code typically requires nodent runtime unless 'noRuntime' or 'spec' option is used

fix

Either include runtime via 'runtimePattern' or set 'compiler.promises: false' if your environment supports Promises.

affects: >=6.0.0

gotchaES7 extensions like 'await' outside async function or 'async return' are not supported because Babel parses the code

fix

Only use standard async/await syntax; those extensions are only available with nodent directly.

affects: >=1.0.0

gotchaStack trace mapping can conflict with Babel's own mapping, causing confusion

fix

Ensure 'dontMapStackTraces' defaults to true; avoid enabling both mappings simultaneously.

affects: >=6.1.0

Errors

Common errors & fixes

Error: Couldn't find preset "es2015" relative to directory ...

Missing Babel presets required by fast-async or configuration error

fix

Ensure babel-preset-es2015 (or equivalent) is installed and listed in .babelrc 'presets'.

TypeError: Cannot read property 'async' of undefined

Plugin loaded incorrectly or Babel version mismatch (e.g., using v6 plugin with Babel 7)

fix

Verify Babel version and install correct fast-async version (v6 for Babel 6, v7 for Babel 7).

SyntaxError: Unexpected token (1:14) ... while parsing async function

Babel parser does not support certain async/await syntax edge cases (e.g., await in non-async function)

fix

Ensure all await expressions are inside async functions. Use standard ES2017 syntax.

Upgrade

Version history

1.1.0latest on npm

Audit

Dependencies

nodentrequiredCore transformation library; provides async/await compilation logic

Agent activity

6 hits · last 30 days

node

Resources

githubhttps://github.com/MatAtBread/fast-async ↗

packagehttps://www.npmjs.com/package/fast-async ↗