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Editorial Team
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Asked: 2026-05-28T18:21:10+00:00

I’m looping through a large object where the internal properties are not all consistent.

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I’m looping through a large object where the internal properties are not all consistent. However, when I throw an if(typeof){} statement around the object, it’s still triggering an error:

The statement

if (typeof pendingTripDropoffMarkers[i].trip.id !== "undefined") {// do stuff}

The error

Uncaught TypeError: Cannot read property 'trip' of undefined

The catch

However, a sister object sitting in the same function with the same scope does just fine.

if (typeof pendingTripPickupMarkers[i].trip.id !== "undefined") {// do stuff}

If I do a print of object contents after they are created, they look just fine. So what evil force has a hand here? Thanks.

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1 Answer

  1. Editorial Team

    You should test any objects that have potential of being undefined.

    if (pendingTripDropoffMarkers[i] 
       && pendingTripDropoffMarkers[i].trip
       && pendingTripDropoffMarkers[i].trip.id !== undefined) {

    If you’re really worried about undefined being overwritten, don’t do the typeof hack. Just get a fresh undefined using the void operator.

    if (pendingTripDropoffMarkers[i] 
       && pendingTripDropoffMarkers[i].trip
       && pendingTripDropoffMarkers[i].trip.id !== void 0) {

    If you’re certain that pendingTripDropoffMarkers[i] should be defined, then there’s some other issue somewhere.

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