Deep copy with custom function https://medium.com/p/58fa3de25130

Deep copy with custom function.js

const customDeepCopy = (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] = customDeepCopy(value);
  }
  return outObject;
};

// Start with a deeply nested array object:
const array = [37, { a: "b" }, { b: { c: "d" } }];
// Make a deep copy with a custom function:
const copy = customDeepCopy(array);
console.info(array); // [37, {a: "b"}, {b: {c: "d"}}]
copy[0] = -0; // Change a primitive value (not nested)
copy[1].a = "y"; // Change a deeply nested value
copy[2].b.c = "z"; // Change another deeply nested value
// Deeply nested objects were actually copied this time:
console.info(array); // [37, {a: "b"}, {b: {c: "d"}}]
// Note how the changes to copy did not affect array:
console.info(copy); // [-0, {a: "y"}, {b: {c: "z"}}]