Why does the element from a nested array in javascript return as undefined when I try to access it?

Question

Why does the element from a nested array in javascript return as undefined when I try to access it?

Struggling to extract elements from a multidimensional array in JavaScript. Running into an issue where attempting to access elements from arrays within the main array using a variable results in undefined. Surprisingly, I achieve the desired outcome when utilizing a number instead of a variable.

let arr = [[1,2,3],[4,5,6],[7,8,9]];

for(let i=0; i < arr.length; i++) {
  console.log(arr[i][arr.length]);
}

javascript arrays multidimensional-array nested

Answer 1

Answer №1

To address the issue of the last array index being 2 when the array length is 3, you can make the following adjustment:

let arr = [[1,2,3],[4,5,6],[7,8,9]];
for(let i=0;i<arr.length;i++){
  console.log(arr[i][arr.length - 1]); // Make sure to subtract 1
}

This code snippet will output 3, 6, 9

Answer 2

To address the issue of the last array index being 2 when the array length is 3, you can make the following adjustment:

let arr = [[1,2,3],[4,5,6],[7,8,9]];
for(let i=0;i<arr.length;i++){
  console.log(arr[i][arr.length - 1]); // Make sure to subtract 1
}

This code snippet will output 3, 6, 9

Answer 3

Answer №2

To access all elements within nested arrays, you'll need to utilize two for loops. One loop will iterate through the main array and another loop inside it will iterate through the inner arrays.

let arr = [[1,2,3],[4,5,6],[7,8,9]];

for(let i=0; i < arr.length; i++) {
  //looping through the outer array
  console.log(arr[i])
  for(let j=0;j< arr[i].length;j++)
  {
    //looping through the inner arrays
    console.log(arr[i][j]);
  }
  
}

Answer 4

To access all elements within nested arrays, you'll need to utilize two for loops. One loop will iterate through the main array and another loop inside it will iterate through the inner arrays.

let arr = [[1,2,3],[4,5,6],[7,8,9]];

for(let i=0; i < arr.length; i++) {
  //looping through the outer array
  console.log(arr[i])
  for(let j=0;j< arr[i].length;j++)
  {
    //looping through the inner arrays
    console.log(arr[i][j]);
  }
  
}

Why does the element from a nested array in javascript return as undefined when I try to access it?

Answer №1

Answer №2

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