Emscripten provides two functions for calling compiled C/C++ functions from JavaScript: ccall() and cwrap(). Both of these functions are present in the Module object. Deciding which one to use is contingent on whether the function will be called more than once. The content in the following sections was taken from Emscripten's API reference documentation for preamble.js, which can be viewed at http://kripken.github.io/emscripten-site/docs/api_reference/preamble.js.html.