The return value from Aarray.map doesn't seem logical

Question

The return value from Aarray.map doesn't seem logical

function replicateArrayWithModification(array, instructions) {
  return array.map(function (element, index, arr) {
    return arr.push(instructions(element));
  });
}
function doubleValue(input) {
 return input * 2;
}
var result = replicateArrayWithModification([1, 2, 3], doubleValue);
console.log(result)

I am perplexed by the fact that the resulting array is [4,5,6], even after debugging I couldn't comprehend how the value 5 manifested. Simply aiming to grasp the origin of this mysterious [4,5,6] array without seeking a solution.

javascript arrays

Answer 1

Answer №1

Utilizing the map method results in a new array being returned, so avoid pushing to <code>arr

within the map function. The multiplied array is already obtained.

function manipulateArray(array, rules) {
    return array.map(function (element, index, arr) {
      return rules(element); // Avoid pushing here
    });
  }
  function double(input) {
    return input * 2;
  }
  var outcome = manipulateArray([1, 2, 3], double);

Answer 2

Utilizing the map method results in a new array being returned, so avoid pushing to <code>arr

within the map function. The multiplied array is already obtained.

function manipulateArray(array, rules) {
    return array.map(function (element, index, arr) {
      return rules(element); // Avoid pushing here
    });
  }
  function double(input) {
    return input * 2;
  }
  var outcome = manipulateArray([1, 2, 3], double);

Answer 3

Answer №2

You are essentially reimplementing map by using map. The map function already performs the functionality of what you've named copyArrayAndManipulate, making it redundant to create an extra layer around an existing function. To make your code functional, all you need to do is remove the arr.push and directly return instructions(element) within the map function. This will result in the map function creating a new "copy" of the array and applying the specified manipulation function to each "element".

Answer 4

You are essentially reimplementing map by using map. The map function already performs the functionality of what you've named copyArrayAndManipulate, making it redundant to create an extra layer around an existing function. To make your code functional, all you need to do is remove the arr.push and directly return instructions(element) within the map function. This will result in the map function creating a new "copy" of the array and applying the specified manipulation function to each "element".

The return value from Aarray.map doesn't seem logical

Answer №1

Answer №2

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