/*
Closure
*/

var createPet = function(name) {
  var sex;
  
  return {
    setName: function(newName) {
      name = newName;
    },
    
    getName: function() {
      return name;
    },
    
    getSex: function() {
      return sex;
    },
    
    setSex: function(newSex) {
      if(typeof newSex === 'string' && (newSex.toLowerCase() === 'male' || 
        newSex.toLowerCase() === 'female')) {
        sex = newSex;
      }
    }
  }
}

var pet = createPet('Vivie');
pet.getName();                  // Vivie

pet.setName('Oliver');
pet.setSex('male');
pet.getSex();                   // male
pet.getName();                  // Oliver


/*
clousure 2
*/
var createPet = function(name) {  // The outer function defines a variable called "name".
  return {
    setName: function(n) {    // The enclosed function also defines a variable called "name".
      name = n;return this;               // How do we access the "name" defined by the outer function?
    }, getName:function(){return name;}
  }
}


/**
arguments
*/
function myConcat(separator) {
   var result = ''; // initialize list
   var i;
   // iterate through arguments
   for (i = 1; i < arguments.length; i++) {
      result += arguments[i] + separator;
   }
   return result;
}
// returns "red, orange, blue, "
myConcat(', ', 'red', 'orange', 'blue');

// returns "elephant; giraffe; lion; cheetah; "
myConcat('; ', 'elephant', 'giraffe', 'lion', 'cheetah');

// returns "sage. basil. oregano. pepper. parsley. "
myConcat('. ', 'sage', 'basil', 'oregano', 'pepper', 'parsley');


/*
arrow function
*/
var a = [
  'Hydrogen',
  'Helium',
  'Lithium',
  'Beryllium'
];

var a2 = a.map(function(s) { return s.length; });

console.log(a2); // logs [8, 6, 7, 9]

var a3 = a.map(s => s.length);

console.log(a3); // logs [8, 6, 7, 9]



/*
the 'this'
*/
function Person() {
  var self = this; // Some choose `that` instead of `self`. 
                   // Choose one and be consistent.
  self.age = 0;

  setInterval(function growUp() {
    // The callback refers to the `self` variable of which
    // the value is the expected object.
    self.age++;
  }, 1000);
}

// same as below arrow function

function Person() {
  this.age = 0;

  setInterval(() => {
    this.age++; // |this| properly refers to the person object
  }, 1000);
}

var p = new Person();