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JavaScript error: Cannot read property 'includes' of undefined

rated 0 times [ 7] [ 7] / answers: 1 / hits: 86459 / 8 Years ago, fri, january 6, 2017, 12:00:00

I want to check if a data.objectId already exists in the array msgArr. For that I am running the code below:

var exists = msgArr.objectId.includes(data.objectId);



if(exists === false){

   msgArr.push({objectId:data.objectId,latLont:data.latLont,isOnline:data.isOnline});

}

The array looks like the following:

var msgArr = [

  {isOnline:true,latLont:123,objectId:on0V04v0Y9},

  {isOnline:true,latLont:1,objectId:FpWBmpo0RY},

  {isOnline:true,latLont:48343,objectId:Qt6CRXQuqE} 

 ]

I am getting the error below:

Cannot read property 'includes' of undefined

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josefn

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answered 8 Years ago berenices · Accepted Answer

As the comments say: the javascript array object has no property objectId.

Looking at the objects in this array it's clear that they have it, so to check if a certain element exists you can do so using Array.prototype.some method:

var exists = msgArr.some(o => o.objectId === data.objectId);