I need to JSON.stringify a possibly cyclic object, which means that I have to pre-process the object and remove cycles. I'm already aware of the n^2 indexOf solution. Since that javascript doesn't seem to expose an object id or memory location, nor a generic hashcode for any object, is there a way to make the containment check faster?
An ES6 Set object can keep track of objects visited directly. As you're traversing through the object, you put each object into the Set and then a simple objSet.has(obj) will tell if you've already encountered this object of not.
Work-arounds when that ES6 Set is not available usually involve adding a non-enumerable uniquely generated string key to each object so you can put that in a regular object map which is shown here in this ES6 Set polyfill.