Custom deep copy function using recursion.js

const deepCopyFunction = (inObject) => {
  let outObject, value, key

  if (typeof inObject !== "object" || inObject === null) {
    return inObject // Return the value if inObject is not an object
  }

  // Create an array or object to hold the values
  outObject = Array.isArray(inObject) ? [] : {}

  for (key in inObject) {
    value = inObject[key]

    // Recursively (deep) copy for nested objects, including arrays
    outObject[key] = deepCopyFunction(value)
  }

  return outObject
}

let originalArray = [37, 3700, { hello: "world" }]
console.log("Original array:", ...originalArray) // 37 3700 Object { hello: "world" }

let shallowCopiedArray = originalArray.slice()
let deepCopiedArray = deepCopyFunction(originalArray)

originalArray[1] = 0 // Will affect the original only
console.log(`originalArray[1] = 0 // Will affect the original only`)
originalArray[2].hello = "moon" // Will affect the original and the shallow copy
console.log(`originalArray[2].hello = "moon" // Will affect the original array and the shallow copy`)

console.log("Original array:", ...originalArray) // 37 0 Object { hello: "moon" }
console.log("Shallow copy:", ...shallowCopiedArray) // 37 3700 Object { hello: "moon" }
console.log("Deep copy:", ...deepCopiedArray) // 37 3700 Object { hello: "world" }