This is the path to the file eval.js. This is required when running in node, and required for some browsers (IE 10) in order to work around cross-domain restrictions for web workers. Defaults to the same location as parallel.js in node environments, and null in the browser.
The maximum number of permitted worker threads. This will default to 4, or the number of cpus on your computer if you're running node.
If webworkers are not available, whether or not to fall back to synchronous processing using setTimeout. Defaults to true.