File object - Archive of obsolete content
getting started in order to use the file object from your javascript programs, you must enable it by setting the make variable js_has_file_object during the compilation of your spidermonkey engine.
... if you are building a standalone version of spidermonkey (see: spidermonkey build documentation), this variable can be added on the make command line, like so: cd mozilla/js/src make -f makefile.ref js_has_file_object=1 alternatively, if you are building a larger product (such as a browser) and want to include the file object, you may need to perform minor makefile surgery.