readme.md

Cloning and transforming state

The guideline

Read the guideline before start

Task description:

Write a transformStateWithClones function that takes a state object and an actions array, applies each action to the previos state to calculate the next state, and returns an array with states recieved after each action.

Each action is an object describing state changes. Depending on a value of its type property you should do the next:

• clear - create an empty state object;
• addProperties - add all key: value pairs given in extraData property to the new state;
• removeProperties - remove all keys given in the keysToRemove array from the state. (ignore not existing)

IMPORTANT! DON'T modify the initial state object in any way!

Example 1:

const state = {
  foo: 'bar',
  bar: 'foo',
};

const stateHistory = transformStateWithClones(state, [
  {
    type: 'addProperties',
    extraData: { name: 'Jim', hello: 'world' },
  },
  {
    type: 'removeProperties',
    keysToRemove: ['bar', 'hello'],
  },
  {
    type: 'addProperties',
    extraData: { another: 'one' },
  },
]);

console.log(stateHistory);
// [
//   { foo: 'bar', bar: 'foo', name: 'Jim', hello: 'world' },
//   { foo: 'bar', name: 'Jim' },
//   { foo: 'bar', name: 'Jim', another: 'one' },
// ]

Example 2:

const state = {
  foo: 'bar',
  bar: 'foo',
};

const stateHistory = transformStateWithClones(state, [
  {
    type: 'addProperties',
    extraData: { yet: 'another property' },
  }
  { type: 'clear' },
  {
    type: 'addProperties',
    extraData: { foo: 'bar', name: 'Jim' },
  },
]);

console.log(stateHistory);
// [
//   { foo: 'bar', bar: 'foo', yet: 'another property' },
//   {},
//   { foo: 'bar', name: 'Jim' },
// ]