cpu-arch

Detect CPU architecture (not process architecture).

Handles emulation scenarios where process.arch returns the wrong value:

• Windows WoW64: 32-bit Node on 64-bit Windows → returns x64
• macOS Rosetta 2: x64 Node on Apple Silicon → returns arm64
• Windows ARM64: Any Node on ARM Windows → returns arm64

Installation

npm install cpu-arch

Usage

const cpuArch = require('cpu-arch');

console.log(cpuArch());
// => 'x64', 'arm64', 'ia32', 'arm', etc.

Why Not process.arch?

process.arch returns the architecture of the Node.js binary, not the CPU:

| Scenario | process.arch | cpuArch() | |----------|----------------|-------------| | 32-bit Node on 64-bit Windows | ia32 | x64 | | x64 Node on Apple Silicon (Rosetta) | x64 | arm64 | | Native arm64 Node on Apple Silicon | arm64 | arm64 |

This matters when selecting native binaries (e.g., @swc/core, Node.js downloads).

Return Values

| Value | Description | |-------|-------------| | x64 | 64-bit Intel/AMD | | arm64 | 64-bit ARM (Apple Silicon, ARM64 Windows/Linux) | | ia32 | 32-bit Intel/AMD | | arm | 32-bit ARM | | ia64 | Intel Itanium | | Other | Raw uname -m output (ppc64, s390x, etc.) |

Platform Detection Methods

| Platform | Method | |----------|--------| | Windows | PROCESSOR_ARCHITEW6432 / PROCESSOR_ARCHITECTURE env vars | | macOS | sysctl -in sysctl.proc_translated for Rosetta detection | | Linux | uname -m |

License

MIT