What could be the reason for the ERROR message saying, "Cannot read property '0' of undefined"?

I'm really struggling to understand why I keep receiving an Undefined error for tagged_Assets. Can someone please shed some light on this for me? Thank you.

Model.ts

export class TaggedAssests {
   device_id: string;
   hasTag: boolean;
}

Component.ts

tagged_Assets: TaggedAssests[];

Usage in Component.ts

for(let i = 0; i < this.temp.length; i++) 
{   
        ERR-> this.tagged_Assets[i].device_id = this.temp[i].device_id;*
        this.tagged_Assets[i].hasTag = true;
}

Answer №1

One approach is to start by setting up the array:

taggedItems: TaggedItems[] = [];

Another option could be to try using the ?. operator for conditional assignment:

this.taggedItems[index]?.name = this.data[index].name;

Answer №2

The main problem here lies in the fact that this.tagged_Assets is currently undefined, making it impossible to access the property device_id

To fix this issue, you need to initialize this.tagged_Assets = [] and adjust your loop block like so:

this.tagged_Assets[i] =  {
    device_id: this.temp[i].device_id,
    hasTag: true
}

Answer №3

Initialize the variable tagged_Assets as an empty array:

tagged_Assets: TaggedAssests[] = [];

Then, you can utilize it in the following manner:

this.tagged_Assets[i] =  {
   device_id: this.temp[i].device_id,
   hasTag: true
}

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