logic.js

// Part 1. Fill in any missing parts of the todoFunction object!
// you can access these on todo.todoFunctions
// For part one we expect you to use tdd

/* USED FOR TESTING
var todos = [
  {id: 0, description: 'make tea', done: true},
  {id: 1, description: 'make eggs', done: true},
  {id: 2, description: 'make coffee', done: false},
  {id: 3, description: 'make bacon', done: true},
]
var newTodo = { description: 'make smoothie' };
// var updatedTodos = addTodo(todos, newTodo);
var idToMark =  2;
var idToDelete =  2;
*/

var todoFunctions = {
  // todoFunctions.generateId() will give you a unique id
  // You do not need to understand the implementation of this function.
  generateId: (function() {
    var idCounter = 0;

    function incrementCounter() {
      return (idCounter += 1);
    }

    return incrementCounter;
  })(),

  //cloneArrayOfObjects will create a copy of the todos array
  //changes to the new array don't affect the original
  cloneArrayOfObjects: function(todos) {
    return todos.map(function(todo) {
      return JSON.parse(JSON.stringify(todo));
    });
  },

  addTodo: function(todos, description) {
      var newTodos = todoFunctions.cloneArrayOfObjects(todos)
      newTodos.push({
        description: description,
        done: false,
        id: todoFunctions.generateId(),
      })
      return newTodos
    // should leave the input argument todos unchanged (you can use cloneArrayOfObjects)
    // returns a new array, it should contain todos with the newTodo added to the end.
    // add an id to the newTodo. You can use the generateId function to create an id.
    // hint: array.concat
  },

  deleteTodo: function(todos, idToDelete) {
    var newTodos = todoFunctions.cloneArrayOfObjects(todos);
    for (let x = 0; x < newTodos.length; x++) {
      if (newTodos[x].id == idToDelete) {
        newTodos.splice(x, 1);
      }
    }
    return newTodos;
  },

  markTodo: function(todos, idToMark) {
    var newTodos = todoFunctions.cloneArrayOfObjects(todos);
    for (let item of newTodos) {
      if (item.id == idToMark) {
        item.done ? (item.done = false) : (item.done = true);
      }
    }
    return newTodos;
  },

  sortTodos: function(todos, sortFunction) {
    // stretch goal! Do this last
    // should leave the input arguement todos unchanged (you can use cloneArrayOfObjects)
    // sortFunction will have same signature as the sort function in array.sort
    // hint: array.slice, array.sort
  }
};

// Why is this if statement necessary?
// The answer has something to do with needing to run code both in the browser and in Node.js
// See this article for more details:
// http://www.matteoagosti.com/blog/2013/02/24/writing-javascript-modules-for-both-browser-and-node/
if (typeof module !== "undefined") {
  module.exports = todoFunctions;
}