Dealing with undefined array sizes in Javascript

Question

Dealing with undefined array sizes in Javascript

I'm struggling to populate an array using a while loop. Even though the length of the array indicates that there is data present, attempting to access the data at specific indices returns undefined.

  var test = [];
  while (i < 16)
  {
    test[i] = i;
    i++;
    console.log(test.length);
    console.log(test[i]);
  }

Console output:

1
Fibbo.html:48 undefined
Fibbo.html:47 2
Fibbo.html:48 undefined
Fibbo.html:47 3
Fibbo.html:48 undefined
Fibbo.html:47 4
Fibbo.html:48 undefined
Fibbo.html:47 5
Fibbo.html:48 undefined
Fibbo.html:47 6
Fibbo.html:48 undefined
Fibbo.html:47 7
Fibbo.html:48 undefined
Fibbo.html:47 8
Fibbo.html:48 undefined
Fibbo.html:47 9
Fibbo.html:48 undefined
Fibbo.html:47 10
Fibbo.html:48 undefined
Fibbo.html:47 11
Fibbo.html:48 undefined
Fibbo.html:47 12
Fibbo.html:48 undefined
Fibbo.html:47 13
Fibbo.html:48 undefined
Fibbo.html:47 14
Fibbo.html:48 undefined
Fibbo.html:47 15
Fibbo.html:48 undefined
Fibbo.html:47 16
Fibbo.html:48 undefined

javascript arrays

Answer 1

Answer №1

To resolve the issue, you need to adjust your code as follows:

  let i = 0;
  const testArray = [];
  
  while (i < 16) {
    testArray[i] = i;
    console.log(testArray.length);
    console.log(testArray[i]);
    i++;
  }

Answer 2

To resolve the issue, you need to adjust your code as follows:

  let i = 0;
  const testArray = [];
  
  while (i < 16) {
    testArray[i] = i;
    console.log(testArray.length);
    console.log(testArray[i]);
    i++;
  }

Answer 3

Answer №2

Make sure to update your code like this:

let numbers = [], index = 0;
while (index < 16)
{
    numbers[index] = index;
    index++;
    console.log(numbers.length);
    console.log(numbers[index-1]);
}

The value of 'index' was being increased after assigning a value to it.

Answer 4

Make sure to update your code like this:

let numbers = [], index = 0;
while (index < 16)
{
    numbers[index] = index;
    index++;
    console.log(numbers.length);
    console.log(numbers[index-1]);
}

The value of 'index' was being increased after assigning a value to it.

Dealing with undefined array sizes in Javascript

Answer №1

Answer №2

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