freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-algorithm-scripting/slice-and-splice.english.md

id, title, isRequired, challengeType, isHidden, forumTopicId

id	title	isRequired	challengeType	isHidden	forumTopicId
579e2a2c335b9d72dd32e05c	Slice and Splice	true	5	false	301148

Description

You are given two arrays and an index. Use the array methods slice and splice to copy each element of the first array into the second array, in order. Begin inserting elements at index n of the second array. Return the resulting array. The input arrays should remain the same after the function runs.

Instructions

Tests

tests:
  - text: <code>frankenSplice([1, 2, 3], [4, 5], 1)</code> should return <code>[4, 1, 2, 3, 5]</code>.
    testString: assert.deepEqual(frankenSplice([1, 2, 3], [4, 5], 1), [4, 1, 2, 3, 5]);
  - text: <code>frankenSplice([1, 2], ["a", "b"], 1)</code> should return <code>["a", 1, 2, "b"]</code>.
    testString: assert.deepEqual(frankenSplice(testArr1, testArr2, 1), ["a", 1, 2, "b"]);
  - text: <code>frankenSplice(["claw", "tentacle"], ["head", "shoulders", "knees", "toes"], 2)</code> should return <code>["head", "shoulders", "claw", "tentacle", "knees", "toes"]</code>.
    testString: assert.deepEqual(frankenSplice(["claw", "tentacle"], ["head", "shoulders", "knees", "toes"], 2), ["head", "shoulders", "claw", "tentacle", "knees", "toes"]);
  - text: All elements from the first array should be added to the second array in their original order.
    testString: assert.deepEqual(frankenSplice([1, 2, 3, 4], [], 0), [1, 2, 3, 4]);
  - text: The first array should remain the same after the function runs.
    testString: frankenSplice(testArr1, testArr2); assert.deepEqual(testArr1, [1, 2]);
  - text: The second array should remain the same after the function runs.
    testString: frankenSplice(testArr1, testArr2); assert.deepEqual(testArr2, ["a", "b"]);

Challenge Seed

function frankenSplice(arr1, arr2, n) {
  return arr2;
}

frankenSplice([1, 2, 3], [4, 5, 6], 1);

After Test

let testArr1 = [1, 2];
let testArr2 = ["a", "b"];

Solution

function frankenSplice(arr1, arr2, n) {
  // It's alive. It's alive!
  let result = arr2.slice();
  for (let i = 0; i < arr1.length; i++) {
    result.splice(n+i, 0, arr1[i]);
  }
  return result;
}

frankenSplice([1, 2, 3], [4, 5], 1);