Checking for the existence of a javascript var inside an array that may or may not exist

Question

I'm trying to check to see if something exists in an array, let's say the array arr is:

{"targeting":{
     "key1":"1",
     "key2":"2"},
 "session": "1234"
}

I want to check to see if arr.targeting.key1 exists so I do:

if (true === !!arr.targeting.key1)

This is true if it exists, but what if arr is empty? Then I get an error:

cannot read properties of undefined, reading 'key1'

What is the simplest way to check for the presence of arr.targeting.key1 that will just return false if arr.targeting or arr themselves are undefined?

You have no arrays, only objects. – Andy Feb 03 '23 at 20:11 — Andy, Feb 03 '23 at 20:11
So check if the object exists before reading its properties – epascarello Feb 03 '23 at 20:15 — epascarello, Feb 03 '23 at 20:15

score 1 · Accepted Answer · answered Feb 03 '23 at 20:13

1

Use optional chaining.

if (arr?.targeting?.key1)

answered Feb 03 '23 at 20:13

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Checking for the existence of a javascript var inside an array that may or may not exist

1 Answers1