jsForth
An implementation of Forth in Javascript
Try it out here
ANS Forth
jsForth implements the full core ANS standard
The following word sets are implemented:
- Core words - fully implemented
- All tests pass except some integer multiplication/division edge cases where the ANS spec differs from the results given by the long package
- Core plus words - fully implemented and all tests pass
- Core extension words - fully implemented and all tests pass
The ANS Forth tests can be run using npm run test or in the intepreter with the following forth code
include test/verbose-tester.fth
include https://raw.githubusercontent.com/gerryjackson/forth2012-test-suite/master/src/core.fr
The complete test suite is available here
js interop
- global variable access
js /document - array access
js .0.2 - property access
js .name - property setting
js .name! - function calling
js .sin{1} - method calling
js /document.getElementById{1} - new with params
js .new{1}
Threading model - trampolined threading
All of the standard threading models require call or jump to execute the next instruction. In js these both translate into functions calls in tail position. Without tail call optimisation this will lead to a stack overflow. Therefore jsForth uses a trampoline to execute instructions.
ECMAScript 6 specifies tail call optimisation but unfortunately most browsers don't support it yet