How to read out the inner array length of a 2 dimensional array in javascript

Question

I need to detect the length of an inner array within a 2d array in my application. But unfortunately it always raises a "TypeError: Cannot read property 'length' of undefined" error. Does anyone detect an error? Thanks a bunch

This is the 2d array called currentNodeData (I get this with the following command --> console.log(currentNodeData)):

And this is how I want to receive the length of the inner array, which should be 6:

console.log(currentNodeData[0].length);

And this is the error:

Answer 1

what is currentNodeData in your case?

lets review:

So we have an Array inside the array.

Lets name it :

const innerArray = [{id:1}, {id: 2}, {id: 3}, {id: 4}]
const outer = [innerArray];

the outer array will have only one inner array? if yes: we can do the next thing:

outer[0].length // 4

or we can use flat()

outer.flat().length // 4

const innerArray = [{id:1}, {id: 2}, {id: 3}, {id: 4}]
const outer = [innerArray];

console.log(outer[0].length);
console.log(outer.flat().length);