This may be a dumb question, but afaik, I don't think there's an API for this. It'd be great if there is Iterable.hasIn() can take in an array to check if a key path exists.

Iterable.has() can't be patched since an array is a valid key.

At the moment, I'm doing something like this:

function pathExists(iterable, path) {

  if(iterable.getIn(path)) {
    return true;
  }
  var notSetValue = true;
  return !(iterable.getIn(path, notSetValue) === notSetValue);
}