assemblyscript

library0.28.18jsnpmunverified

AssemblyScript compiles a strict variant of TypeScript to WebAssembly using Binaryen. Current stable version is 0.28.x, released quarterly. It generates lean and mean WebAssembly modules while being just an npm install away. Key differentiators vs. Emscripten or Rust/Wasm: uses TypeScript-like syntax, has a dedicated standard library, and a runtime optimized for Wasm. Targets Node.js >=20 and npm >=10.

devops

npm install assemblyscript

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · ASSEMBLYSCRIPT

assemblyscript

devopsjavascriptv0.28.18

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.

Asc

✓ import { Asc } from 'assemblyscript'

✗ const Asc = require('assemblyscript')

AssemblyScript is ESM-only. Use named import for the compiler CLI.

compile

✓ import { compile } from 'assemblyscript'

✗ const compile = require('assemblyscript').compile

Use named import for the compiler function.

binaryen

✓ import binaryen from 'assemblyscript'

✗ import * as binaryen from 'assemblyscript'

Default import gives the binaryen module.

transform

✓ import { Transform } from 'assemblyscript/dist/transform'

✗ import { Transform } from 'assemblyscript'

Transform is in a subpath export.

Compiles a simple AssemblyScript function to Wasm binary using the compiler API.

import { compile } from 'assemblyscript'; const result = compile('export function add(a: i32, b: i32): i32 { return a + b; }', { optimize: 3, exportAll: true }); const wasm = result.binary; console.log(wasm.length);

Debug

Known issues

breakingIn v0.27, the compiler API changed from synchronous to async.

fix

Use async/await with compile().

affects: >=0.27

deprecatedRuntime functions like __new are deprecated in favor of new operator.

fix

Use new instead of manual runtime calls.

affects: >=0.28

gotchaAssemblyScript enforces strict type checking at compile time; you cannot use Any or dynamic types.

fix

Use proper concrete types (e.g., i32, f64, string).

affects: *

gotchaGlobal variable initializers must be constants, not expressions.

fix

Use static class fields or inline initialization where possible.

affects: *

gotchaAssemblyScript does not support closures or garbage collection in the traditional sense; memory must be manually managed.

fix

Use Array and Map from the standard library for automatic memory management.

affects: *

Errors

Common errors & fixes

ERROR: Cannot find module 'assemblyscript'

Package not installed in current project.

fix

npm install assemblyscript

TypeError: (intermediate value).compile is not a function

Using ESM import incorrectly with CommonJS require.

fix

Use `import { compile } from 'assemblyscript'` instead of require.

ERROR: Unknown option '--optimize'

Using a flag that does not exist in the current version.

fix

Check documentation for correct CLI flags; use `--optimizeLevel` instead.

ERROR: AssemblyScript runtime is not initialized

Trying to use runtime functions without calling `__initialize()` or using `export function` without proper setup.

fix

Use `export function` and ensure the generated Wasm includes the runtime.

Upgrade

Version history

0.28.18latest on npm

Audit

Dependencies

binaryenrequiredWebAssembly optimizer used during compilation

Agent activity

16 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/AssemblyScript/assemblyscript ↗

packageassemblyscript ↗

homepagehttps://assemblyscript.org ↗