How to check if object sub-children is defined?

Question

My variable a in some scenarios have branch b and in some other - has not. How can I check if a.b.c is defined?

// scenario 1
var a = {
  b: {
    c: "d"
  }
}

// scenario 2
var a = {}

I tried using typeof but without success:

if (typeof a.b.c != 'undefined') {
  console.log('y', a.b.c)
} else {
  console.log('x', a.b.c)
}

score 0 · Answer 1 · edited May 05 '19 at 02:45

0

You can just use if (a.b.c != undefined).

edited May 05 '19 at 02:45

Wai Ha Lee

answered May 04 '19 at 20:04

ancarofl6

I'm getting Error `"Cannot read property 'c' of undefined",` – curious May 04 '19 at 20:10
Ah, right. ```if (a.b != undefined && a.b.c != undefined)``` should work then. That checks both if a.b is defined and if a.b.c is defined. Up to you whether you need both or only the first part . – ancarofl6 May 04 '19 at 20:12
I got it to work with `((a || {}).b || {}).c;` which is pretty cool (from question from duplicate). – curious May 04 '19 at 20:18

1 Answers1