If "a_b" does not exist then the following code throws back undefined - which is what I want:
var abc= json.reduce((a,c) => a.concat({xyz:c.a_b}), [])
However, if I do the following code and look for "media" within "a_b" that does not exist then I get a failure "Cannot read property 'media' of undefined".
var abc= json.reduce((a,c) => a.concat({xyz:c.a_b.media}), [])
Why is this the case?
In both cases "a_b" does not exist yet it is ok with the code if I just call that but not if I try and look for a property within it.
Is there a way to get around this?
For example, I am trying to use "|| null" but that doesn't seem to work within a concat, as below.
var abc= json.reduce((a,c) => a.concat({xyz:c.a_b.media || null}), [])