Bonfire Steamroller

Author

Created by Rafase282

Github | FreeCodeCamp | CodePen | LinkedIn | Website | My Original Wiki

Details

• Difficulty: 2/5

Flatten a nested array. You must account for varying levels of nesting.

Remember to use RSAP if you get stuck. Try to pair program. Write your own code.

Useful Links

• Array.isArray()

Problem Script:

function steamroller(arr) {
  // I'm a steamroller, baby
  return arr;
}

steamroller([1, [2], [3, [[4]]]]);

Explanation:

This problem seems simple but you need to make sure to flatten any array, regardless of the level which is what adds a bit of difficulty to the problem.

Hint: 1

You need to check if an element is an array or not.

Hint: 2

If you are dealing with an array, then you need flatten it by getting the value inside of the array. This means if you have 4 then instead of returning [4] you need to return 4. If you get [4] then the same, you want the 4. You can access it with arr[index1][index2] to go a level deeper.

Hint: 3

You will definitely need recursion or another way to go beyond two level arrays to make the code flexible and not hard-coded to the answers needed. Have fun!

My code:

function steamroller(arr) {
  var flattenedArray = [];

  // Create function that adds an element if it is not an array.
  // If it is an array, then loops through it and uses recursion on that array.
  var flatten = function(arg) {
    if (!Array.isArray(arg)) {
      flattenedArray.push(arg);
    } else {
      for (var a in arg) {
        flatten(arg[a]);
      }
    }
  };

  // Call the function for each element in the array
  arr.forEach(flatten);
  return flattenedArray;
}

My Code Explanation:

• Create a new variable to keep flattened arrays.
• Create a function that will add non array elements to the new variable, and for the ones that are array it loops through them to get the element.
• It does that by using recursion, if the element is an array then call the function again with a layer of array deeper to check if it is an array or not. if it is not then push that non-array element to the variable that gets returned. Otherwise, keep going deeper.
• Use Array.forEach(callbackFunc) to go element by element of the original array.
• Return the flattened array.

Go Home