callbackAndHigherOrder.js

//////// PROBLEM 1 ////////

/*
  Write a function called multiply that takes in three parameters: two numbers and a callback function.  
  Invoke the callback, passing in the product of the two numbers multiplied as the argument. 
*/

// CODE HERE

const multiply = (num1, num2, callBack) => {
  return callBack(num1 * num2)
};

// UNCOMMENT THE FUNCTION CALL BELOW
// RUN THIS FILE WITH NODE
// CHECK YOUR ANSWER

multiply(4, 3, answer => {
  console.log('The answer is ' + answer) //should console.log 12
})



////////// PROBLEMS 2 - 6 //////////

// The names array will be used in problems 2 - 6.

// Do not edit the code below.
var names = ['Tyler', 'Cahlan', 'Ryan', 'Colt', 'Tyler', 'Blaine', 'Cahlan']
// Do not edit the code above.



////////// PROBLEM 2 //////////

/*
  Write a function called first that takes in two parameters, an array and a callback function.
  Then invoke the callback function, passing in the first element in the array as it's argument.
*/

// CODE HERE 

const first = (arr, callBack) => {callBack(arr[0]);}

// UNCOMMENT THE FUNCTION CALL BELOW
// RUN THIS FILE WITH NODE
// CHECK YOUR ANSWER

first(names, firstName => {
  console.log('The first name in names is ' + firstName)
})



////////// PROBLEM 3 //////////

/*
  Write a function called last that takes in an array and a callback function. 
  Then invoke the callback, passing in the last element in the array as the argument.
*/

// CODE HERE

// const last = (arr, callBack) => {
//   return callBack(arr[6]);
// }

const last = (arr, callBack) => {
  return callBack(arr[arr.length - 1]);
}

// UNCOMMENT THE FUNCTION CALL BELOW
// RUN THIS FILE WITH NODE
// CHECK YOUR ANSWER

last(names, lastName => {
  console.log('The last name in names is ' + lastName)
})



////////// PROBLEM 4 //////////

/*
  Write a function called contains that takes in three parameters: an array, a name and a callback.  
  Check if the name exists in the array. 
  If it does, invoke the callback with true as the argument. 
  If the name does not exist, invoke the callback with false as the argument.
*/

// CODE HERE 

const contains = (arr, name, callback) => {
  if (arr.includes(name)) {
    return callback(true);
  } else {
    return callback(false);
  }
}

// UNCOMMENT THE FUNCTION CALL BELOW
// RUN THIS FILE WITH NODE
// CHECK YOUR ANSWER

contains(names, 'Colt', result => {
  if (result === true) {
    console.log('Colt is in the array')
  } else {
    console.log('Colt is not in the array')
  }
})

////////// PROBLEM 5 //////////

/*
  Write a function called uniq that takes in an array and a callback function.
  Remove any duplicate values from the array, and invoke the callback with the modified array as an argument.
  Hint: you can use a nested for loop to do this.
*/

// CODE HERE

const uniq = (arr, callBack) => {
  // let unique = new Set(arr);
  for (let i = 0; i < arr.length; i++) {
    for (let j = i + 1; j < arr.length; j++) {
      if (arr[i] === arr[j]) {
        arr.splice(j, 1);
        j--;
      }
    }
  }
  callBack(arr);
}

//Different solutions below
const unique = (arr, cb) => {
  // let mySet = new Set();
  // let arrSet = mySet.add(arr)
  // let mySpread = [...mySet];

  // let uniqueArray = [...new Set(arr)];

  // let uniqueArray = arr.filter((name, index) => {
  //     return arr.indexOf(name) == index;
  // });

  cb(uniqueArray);
};


/*
  Invoke the uniq function, passing in the names array from above and a callback function.
  The callback function should take in one parameter called uniqArr.
  The callback should print a string that says:
  'The new names array with all the duplicate items removed is [UNIQARRPARAM].'
*/

// CODE HERE

uniq(names, (uniqArr) => {
  console.log(`The new names array with all the duplicate items removed is ${uniqArr}`)
})


////////// PROBLEM 6 //////////

/* 
  Write a function called each that takes in an array of names and a callback function. 
  For each name in the array, invoke the callback and pass in the name and the name's index as arguments.
*/

// CODE HERE 

const each = (arr, callBack) => {
  arr.forEach(function (element, index) {
    return callBack(element, index);
  });
}

/*
  Invoke the each function, passing in the names array and a callback function.
  The callback function should take in two parameters, item and index.
  The callback should print a string that says:
  'The item at index [INDEXPARAM] is [ITEMPARAM].'
*/

// CODE HERE

each(names, (item, index) => {
  console.log(`The item at index ${index}  is ${item} `);
})

////////// PROBLEM 7 //////////

/*
  Write a function called getUserById that takes in three parameters: an array of objects (users), an id and a callback, and searches for the user with a matching id.
  When the correct user object is found, invoke the callback with the user object as an argument.
*/

// Do not edit the code below.
var users = [{
    id: '12d',
    email: 'tyler@gmail.com',
    name: 'Tyler',
    address: '167 East 500 North'
  },
  {
    id: '15a',
    email: 'cahlan@gmail.com',
    name: 'Cahlan',
    address: '135 East 320 North'
  },
  {
    id: '16t',
    email: 'ryan@gmail.com',
    name: 'Ryan',
    address: '192 East 32 North'
  },
]
// Do not edit the code above.

// CODE HERE 

const getUserById = (arr, id, callBack) => {
    for (let i = 0; i < arr.length; i++) {

      if (arr[i].id === id) {
        return callBack(arr[i])
      }
    }
  }

    // UNCOMMENT THE FUNCTION CALL BELOW
    // RUN THIS FILE WITH NODE
    // CHECK YOUR ANSWER

    getUserById(users, '16t', user => {
      console.log('The user with the id 16t has the email of ' + user.email + ' the name of ' + user.name + ' and the address of ' + user.address) 
    })

    ////////// CHALLENGE //////////

    /*
      You'll be writing a higher order function that returns
      another function. 

      Create a function called addingFactory that takes in
      one parameter (it will be a number).

      addingFactory should return a function that takes in
      one parameter (this will be another number).

      The (inner) function that's being returned should add
      the two parameters together and return the sum.
    */

    // CODE HERE
const addingFactory = x => y => x + y

const addingFactory = (x) => (y) => x + y;

const addingFactory = x => {
    return function(y) {
        return x + y
    }
}

    /*
      Now that you have addingFactory, you can create other
      functions from it. 

      You're going to invoke addingFactory and save the result
      to a new variable. 

      Create a variable called addTen and set it equal to 
      the invocation of addingFactory passing in the number
      10 as an arguemnt.
    */

    // CODE HERE

const addTen = addingFactory(10)

    /*
      Now the inner function is stored in the addTen variable! 

      Call the addTen function passing in another number and
      console log the result.

      Call it a second time, passing in a different number
      to see the different outputs.
    */

    // CODE HERE

console.log(addTen(333))
console.log(addTen(737373))

    /*
      Let's make another function from the addingFactory. 

      This time, pass in your favorite number and name
      the variable addNUMBER with the name of the number
      you chose. 

      Once you create that, you can invoke the function
      to add any number to your favorite number!
    */

    // CODE HERE

const addSeven = addingFactory(7)

console.log(addSeven(7))
console.log(addSeven(777))