This is CLIPS a productive development and delivery expert system tool which provides a complete environment for the construction of rule and/or object based expert systems. (CLIPS Home) CLIPS.js is the original C version compiled to JS by emscripten. It runs in your browser, so 'javascript' has to be enabled. Beware, some slow connections need some seconds to load the 10MB js file. (Quick Ref.) You can get it from here.