Cannot set property of undefined TypeScript

Question

I want to set object with data and then pushed it to another object

let globalSamples = {} as any;
let sample = { } as ISamplesDetail [];
sample = [];
for (let i = 0 ; i<this.prelevementLingette.samplesDetail.length; i++)
    {
      sample [i].id= this.old.samplesDetail[i].id;
      sample [i].reference=this.old.samplesDetail[i].reference;
}
globalSamples.push(sample);

I got this error 'Cannot set property 'reference' of undefined'

How can I resolve the problem ?

use an if statement. something like if (!sample[i]) continue; in order to jump to the next iteration if sample[i] is null or undefined. — Zoti
– Zoti, Commented Dec 19, 2017 at 14:52

Daniel Khoroshko · Accepted Answer · 2017-12-19 14:54:58Z

1

There are a few problems in your code, so I've cleaned it up a bit

// looks like this would be a proper type..
const globalSamples: ISamplesDetail[][] = [];

// can't assign object ({}) what should be an array, so..
// value doesn't change -> const
const sample: ISamplesDetail[] = [];


// it's strange that you iterate over 'this.prelevementLingette',
// but access 'this.old'
for (let i = 0 ; i < this.prelevementLingette.samplesDetail.length; i++) {
      sample[i] = {
          id: this.old.samplesDetail[i].id,
          reference: this.old.samplesDetail[i].reference
      }
}

// can't push to an object (should be array - [])
globalSamples.push(sample);

It seems like the logic in your code is a bit twisted, but it's difficult to say without knowing the context

answered Dec 19, 2017 at 14:54

Daniel Khoroshko

2,7411 gold badge20 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Hamdy Over a year ago

It works! What do we call this syntax ? And Why my code doesn't work. It's seems the same

Daniel Khoroshko Over a year ago

what syntax exactly?

Collectives™ on Stack Overflow

Cannot set property of undefined TypeScript

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related