Manually Building Emscripten on Mac OS X¶

What you’ll need¶

The specific versions of tools that are needed are listed in the Emscripten Toolchain Requirements.

Installing required tools¶

These instructions explain how to install all the required tools. You can test whether some of these are already installed on the platform and skip those steps.

1. Install the XCode Command Line Tools. These include the toolchain to build Fastcomp, and are a precondition for git.

   • Install XCode from the Mac OS X App Store.
   • In XCode | Preferences | Downloads, install Command Line Tools.

2. Install git:

   • Allow installation of unsigned packages, or installing the git package won’t succeed.
   • Install XCode and the XCode Command Line Tools (should already have been done). This will provide git to the system PATH (see this stackoverflow post).
   • Download and install git directly from http://git-scm.com/.

3. Install cmake if you do not have it yet:

   • Download and install cmake-2.8.10.2-Darwin64-universal.dmg.

   Tip

   This specific version (2.8.10) is recommended — it has been tested and shown to work. Other versions may not correctly set up the PATH variables, with the result that running cmake gives you “not found” errors.

4. Install node.js from http://nodejs.org/

5. Setup python2 (this step is needed to workaround a bug reported in #763):

   • In terminal, type python2 --version. If you get a “command not found”, type the following:

     cd /usr/bin
     sudo ln python python2
     sudo ln ../../System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7 python22.7
     

   • Enter python2 --version again. It should now print Python 2.7.2

6. Build Fastcomp (LLVM + Clang) from source using these instructions.

7. Clone the kripken/emscripten repository from Github. This repository contains the main compiler tool for compiling C/C++ programs to JavaScript:

   • Create a directory (with no spaces in the name) to contain the clone.

   • Enter the following command into the terminal:

     git clone https://github.com/kripken/emscripten.git
     

Configuring Emscripten settings¶

Almost all the compiler settings used by Emscripten are defined in the compiler configuration file (~/.emscripten), a user-specific file located in the user’s home directory.

Instructions for creating and manually configuring up this file are given in Configuring Emscripten Settings when Manually Building from Source.

Validating the environment¶

The best way to validate the environment is to build some code. Open the terminal in your Emscripten directory (where emcc is located) and enter:

./emcc tests/hello_world.cpp

If this builds a.out.js in the current directory, and you don’t see any build errors in the terminal, Emscripten is good to go!

There are additional validation and troubleshooting instructions in the topic: Verifying the Emscripten Development Environment.