Day 3: Polyfill for Array.flat()

#day3 #100daysofcode #javascript

Today, we'll create a polyfill for the Array.flat() method.
The Array.flat() method flattens nested arrays to a specified depth. Our goal is to create a function called myFlat that will implement this behavior.

// Test cases
const array = [1, [2], [3, [3]]];

console.log(array.myFlat()); // Output: [1, 2, 3, [3]]
console.log(array.myFlat(1)); // Output: [1, 2, 3, [3]]
console.log(array.myFlat(3)); // Output: [1, 2, 3, 3]
console.log(array.myFlat(Infinity)); // Output: [1, 2, 3, 3]

Plan

To solve this problem, we'll follow these steps:

Implement the myFlat function to recursively flatten the array.
The myFlat function will take an optional depth parameter that specifies the depth to which the array should be flattened.
Check if the Array.prototype.myFlat property exists.
If it doesn't exist, create a new property called myFlat on Array.prototype and assign it a function.

Check the comment below to see answer.

Top comments (1)

Dharan Ganesan • Jul 11 '23

// Check if Array.prototype.myFlat exists
if (!Array.prototype.myFlat) {
  Array.prototype.myFlat = function (depth = 1) {
    // Function to flatten the array recursively
    const flatten = (arr, currentDepth) => {
      // Base case: depth reached or array is not an array
      if (currentDepth === 0 || !Array.isArray(arr)) {
        return arr;
      }

      // Recursive case: flatten each element in the array
      return arr.reduce((result, element) => {
        if (Array.isArray(element)) {
          return result.concat(flatten(element, currentDepth - 1));
        }
        return result.concat(element);
      }, []);
    };

    return flatten(this, depth);
  };
}

// Test cases
const array = [1, [2], [3, [3]]];

console.log(array.myFlat()); // Output: [1, 2, 3, [3]]
console.log(array.myFlat(1)); // Output: [1, 2, 3, [3]]
console.log(array.myFlat(3)); // Output: [1, 2, 3, 3]
console.log(array.myFlat(Infinity)); // Output: [1, 2, 3, 3]

DEV Community

Day 3: Polyfill for Array.flat()

Plan

Top comments (1)

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