java-asm

library0.0.6jsnpmunverified

A TypeScript migration of the Java ASM bytecode manipulation framework, targeting v0.0.6 as the latest release (no regular cadence). This library reads Java class files and exposes parsed structures like annotations, methods, and fields. It is unstable and incomplete: only read operations are supported, write functions are explicitly broken. Compared to the original Java ASM, this port is limited and experimental, maintained by a single developer with no guarantees. Best suited for small-scale annotation reading tasks.

devops

npm install java-asm

package ↗

INSTALL

IMPORT

SIG · JAVA-ASM

java-asm

devopsjavascriptv0.0.6

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.

ClassReader

✓ import { ClassReader } from 'java-asm'

✗ const ClassReader = require('java-asm')

ESM-only; no CommonJS support.

ClassVisitor

✓ import { ClassVisitor } from 'java-asm'

✗ const ClassVisitor = require('java-asm').ClassVisitor

ESM-only; requires named import.

Opcodes

✓ import { Opcodes } from 'java-asm'

✗ import * as asm from 'java-asm'; const Opcodes = asm.Opcodes;

Direct named import is correct; the wrong pattern is unnecessarily verbose but works.

Reads a Java class file (as ArrayBuffer) and prints class name, super class, and method signatures.

import { ClassReader } from 'java-asm'; const classBytes = new ArrayBuffer(8); // placeholder const reader = new ClassReader(classBytes); const classFile = reader.read(); console.log(classFile.className, classFile.superClass); for (const method of classFile.methods) { console.log('Method:', method.name, method.desc); }

Debug

Known issues

deprecatedWrite functions are broken and unmaintained.

fix

Use a different library like javy-jvm for writing class files.

affects: >=0.0.0

gotchaOnly works with Java class files (not JAR, not live JVM).

fix

Ensure input is .class file bytes; for JAR, extract entries first.

affects: >=0.0.0

gotchaThe library is unstable and may produce incorrect results for complex class files.

fix

Test thoroughly with your class files; prefer production-ready solutions.

affects: >=0.0.0

Errors

Common errors & fixes

TypeError: ClassReader is not a constructor

Using CommonJS require instead of ESM import.

fix

Use import { ClassReader } from 'java-asm' in an ESM context.

Cannot find module 'java-asm'

Package is not installed or not in node_modules.

fix

Run npm install java-asm --save (but note it's deprecated).

Upgrade

Version history

0.0.6latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

10 hits · last 30 days

node

Resources

packagejava-asm ↗