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

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, newTodo) {
    // 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

    var todo = todoFunctions.cloneArrayOfObjects(todos);
    var newTodo = {id:todoFunctions.generateId(), description: newTodo,done: false };
    todo.push(newTodo);
    return todo;

  },


  deleteTodo: function(todos, idToDelete) {
    // should leave the input argument todos unchanged (you can use cloneArrayOfObjects)
    // return a new array, this should not contain any todo with an id of idToDelete
    // hint: array.filter
    var todoo = todoFunctions.cloneArrayOfObjects(todos);
      todoo=todoo.filter(function(todo){
          return todo.id !=idToDelete;
});

    return todoo;
  },
  markTodo: function(todos, idToMark) {
    // should leave the input argument todos unchanged (you can use cloneArrayOfObjects)
    // in the new todo array, all elements will remain unchanged except the one with id: idToMark
    // this element will have its done value toggled
    // hint: array.map
    var to_do = todoFunctions.cloneArrayOfObjects(todos);
    to_do = to_do.map(function(x) {
      if (x.id ==idToMark) {
        x.done =!x.done;
      }
      return x;
    });
      return to_do;
  },
  sortTodos: function(todos, id) {
    var todoo = todoFunctions.cloneArrayOfObjects(todos);
      todoo=todoo.filter(function(todo){
          return todo.id ==id;
});

    return todoo;
    // 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;
}