--description--

The splice() method can modify arrays by adding or removing elements at any position, including the middle. Since splice() returns an array containing the removed elements, you can use it to swap two elements in an array without mutating the original. This can be done in one line using the following technique:

// swap elements at i and j without mutating the original
const copy = array.slice();
copy[i] = copy.splice(j, 1, copy[i])[0];

Here is an example:

const originalArray = [12, 97, 68, 55];
const copyArray = originalArray.slice();
copyArray[1] = copyArray.splice(3, 1, copyArray[1])[0];
console.log(copyArray); // [12, 55, 68, 97]

The technique, applied in the third line, works as follows:

splice(3, 1, copyArray[1]) removes the element at index 3 (55)
It inserts the element from copyArray[1] (97) into index 3
splice() returns [55], an array containing the removed element
[0] extracts 55 from that array
That value (55) is assigned back to copyArray[1], completing the swap

Use this technique with the updatedCrew array to swap the astronauts at fromIndex and toIndex.

--hints--

You should perform the swap by calling the splice() method.

assert.match(swapCrewMembers.toString(), /splice\s*\(/);

You should call splice() with the updatedCrew array to perform the swap. You should use the one-line technique.

const cleaned = __helpers.removeWhiteSpace(__helpers.removeJSComments(swapCrewMembers.toString()));
const regex = /updatedCrew\[(fromIndex|toIndex)\]=updatedCrew\.splice\((fromIndex|toIndex),1,updatedCrew\[\1\]\)\[0\];?\s*\}$/;
assert.match(cleaned, regex);

Your swapCrewMembers function should not mutate the original input crew array.

const demo = [{ id: 1 }, { id: 2 }, { id: 3 }];
swapCrewMembers(demo, 0, 2);
assert.deepEqual(demo.map(a => a.id), [1, 2, 3]);

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const squad = [];

const firstAstronaut = {
  id: 1,
  name: "Andy",
  role: "Commander",
  isEVAEligible: true,
  priority: 3
};

function addCrewMember(crew, astronaut) {
  for (let i = 0; i < crew.length; i++) {
    if (crew[i].id === astronaut.id) {
      console.log("Duplicate ID: " + astronaut.id);
      return;
    }
  }
  crew.push(astronaut);
}

addCrewMember(squad, firstAstronaut);

const remainingCrew = [
  { id: 2, name: "Bart", role: "Pilot", isEVAEligible: false, priority: 8 },
  { id: 3, name: "Caroline", role: "Engineer", isEVAEligible: true, priority: 4 },
  { id: 4, name: "Diego", role: "Scientist", isEVAEligible: false, priority: 1 },
  { id: 5, name: "Elise", role: "Medic", isEVAEligible: true, priority: 7 },
  { id: 6, name: "Felix", role: "Navigator", isEVAEligible: true, priority: 6 },
  { id: 7, name: "Gertrude", role: "Communications", isEVAEligible: false, priority: 4 },
  { id: 8, name: "Hank", role: "Mechanic", isEVAEligible: true, priority: 2 },
  { id: 9, name: "Irene", role: "Specialist", isEVAEligible: true, priority: 5 },
  { id: 10, name: "Joan", role: "Technician", isEVAEligible: false, priority: 1 },
];

for (let i = 0; i < remainingCrew.length; i++) {
  addCrewMember(squad, remainingCrew[i]);
}

function swapCrewMembers(crew, fromIndex, toIndex) {
  if (
    fromIndex < 0 || 
    toIndex < 0 ||
    fromIndex >= crew.length ||
    toIndex >= crew.length
  ) {
    console.log("Invalid crew indices");
    return;
  }

  const updatedCrew = crew.slice();
--fcc-editable-region--

--fcc-editable-region--
}

Step 12

--description--

--hints--

--seed--

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