shallow and deep clone objects with inheritance

inheritance.js

// shallow copy
function cloneWithProto (source, target = {}) {
  // if you just want to copy the source the target is optional
  
  let clone = {...source, ...target}
  // make shallow copy out of source, and overwrite with target
  
  Object.setPrototypeOf(clone, Object.getPrototypeOf(source))
  // set the proto of result to the proto of source object
  return clone
}

// deep copy
function deepCloneWithProto (source, target = {}) {
  
  const clone_source = JSON.parse(JSON.stringify(source))
  // deep clone source
  const clone_target = JSON.parse(JSON.stringify(target))
  // deep clone target
  
  let result_clone = {...clone_source, ...clone_target}
  // concatenate the deep clones together
  
  Object.setPrototypeOf(result_clone, Object.getPrototypeOf(source))
  // set the proto of result_clone to the proto of source object
  // and not the deep clone of source
  
  return result_clone
}