I've made an example html / javascript rule engine for a product configurator. The rule engine is based on if then statements. The if then statements will be checked with an array. This array is filled with all possible options every time an options is changed.
Check out my blog for the example.
Link to my blog "Forward chaining javascript rule engine"
I think the "obj[key] = val" is the key to a javascript rule engine. Jquery helps with javascript handling.
