export function updateNestedObject()

in glean/src/core/storage.ts [129:164]

• 22 lines of code
• 4 McCabe index (conditional complexity)

export function updateNestedObject(
  obj: JSONObject,
  index: StorageIndex,
  transformFn: (v?: JSONValue) => JSONValue
): JSONObject {
  if (index.length === 0) {
    throw Error("The index must contain at least one property to update.");
  }

  const returnObject = { ...obj };
  let target = returnObject;

  // Loops through all the keys but the last.
  // The last is the key we will **set**, not **get**.
  for (const key of index.slice(0, index.length - 1)) {
    if (!isObject(target[key])) {
      target[key] = {};
    }

    // Typescript throws an error below about not being able to
    // set target to target[key] because it may not be a JSONObject.
    // We make sure by the above conditional that target[key] is a JSONObject,
    // thus we can safely ignore Typescripts concerns.
    //
    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
    // @ts-ignore
    target = target[key];
  }

  const finalKey = index[index.length - 1];
  const current = target[finalKey];

  const value = transformFn(current);
  target[finalKey] = value;
  return returnObject;
}