Accessing Hierarchy Data in an Object Javascript

Question

I need to access the id value in a Javascript object to display a simple message that the user has membership if the id value equals a specific value.

I'm getting Uncaught Type Error not defined 'id' message

In the console it's displayed as

subscriptions: Array(1)
     0: // COMMENT Don't know what this is
       autoRenew: false
       canRenew: false
       expiryDate: "2022-10-26T00:00:00"
       membership:
                 id: "819AGBHDRLQHNHPHKKMPKLGPMDRDTDMVL"

I'm assuming equivalent JSON is something like:

subscriptions {
    0
           {
       membership: {
           id: "819AGBHDRLQHNHPHKKMPKLGPMDRDTDMVL"
}
}
}

My Javascript Code

const userObj3 = userObj['subscriptions']['0']['membership']['id'];

if (userObj3 = "819AGBHDRLQHNHPHKKMPKLGPMDRDTDMVL") {
  greeting = "You have membership";
}