The instructions below list the main tools and dependencies in an Emscripten environment, along with instructions on how to test which dependencies are installed.
The SDK provides the easiest and most reliable method for getting, using, updating and managing Emscripten environments. If you're using the SDK you won't need these instructions — they are provided for information only.
The instructions below are useful if you're manually building from source.
In general a complete Emscripten environment requires the following tools. First test to see if they are already installed using the instructions below.
Node.js (0.8 or above; 0.10.17 or above to run websocket-using servers in node):
Python 2.7.12 or above, or Python 3.5 or above (Python 2.7.0 or newer may also work, but is known to have SSL related issues, https://github.com/emscripten-core/emscripten/issues/6275)
Git client. Git is required if building tools from source.
LLVM (LLVM, including clang and wasm-ld)
Binaryen (Binaryen, including wasm-opt, wasm-emscripten-finalize, etc.)
The Emscripten code, from GitHub
The Spidermonkey shell is also required if you want to run 100% of the tests in the test suite. Most developers will not need this, and should instead use node.js.
When building Emscripten from source code, whether "manually" or using the SDK, you will need a compiler toolchain:
SDK users can also install and activate the MinGW compiler toolchain in order to build their own projects:
emsdk install mingw-4.6.2-32bit emsdk activate mingw-4.6.2-32bit
Linux: Install gcc and cmake:
#Install gcc sudo apt-get install build-essential # Install cmake sudo apt-get install cmake
macOS: Install the Xcode Command Line Tools:
Install Xcode from the macOS App Store.
In Xcode | Preferences | Downloads, install Command Line Tools.
Building LLVM and Clang from source can require a lot of memory and hard drive space. The specific requirements change from LLVM version to another, but you probably need at least 2GB of RAM, preferably 4GB or more. Debug builds or builds with assertions can require even more memory.
Some of the tools are pre-installed on the various platforms (for example, Python is always available on Linux builds).
You can check which tools are already present using the following commands:
# Check for Python python --version # Check for node.js on Linux nodejs --version # Check for node.js on Windows node --version # Check for node.js on macOS node -v # Check for git git --version # Check for Java java -version # Check for gcc / g++ gcc --version g++ # Check for cmake cmake