Javascript: Profile Lookup from freecodecamp

Question

This is my answer in freecodecamp "Basic Javascript: Profile Lookup" (third day trying javascript using Udemy and freecodecamp).

My problem with the code is the huge number of lines on my lookUpProfile function. I would like to minimize the lines of code of my lookUpProfile function, can you suggest me ways to achieve that?

//Setup
var contacts = [
    {
        "firstName": "Akira",
        "lastName": "Laine",
        "number": "0543236543",
        "likes": ["Pizza", "Coding", "Brownie Points"]
    },
    {
        "firstName": "Harry",
        "lastName": "Potter",
        "number": "0994372684",
        "likes": ["Hogwarts", "Magic", "Hagrid"]
    },
    {
        "firstName": "Sherlock",
        "lastName": "Holmes",
        "number": "0487345643",
        "likes": ["Intriguing Cases", "Violin"]
    },
    {
        "firstName": "Kristian",
        "lastName": "Vos",
        "number": "unknown",
        "likes": ["Javascript", "Gaming", "Foxes"]
    }
];


function lookUpProfile(firstName, prop){
// Only change code below this line

  var contain = 0;
  if(firstName == "Akira"){
    contain = 0;
    if(contacts[contain].firstName == firstName)
      if(contacts[contain].hasOwnProperty(prop))
        return contacts[contain][prop];
      else
        return "No such property";
    else
      return "No such contact";
  }
  else if(firstName == "Harry"){
    contain = 1;
    if(contacts[contain].firstName == firstName)
      if(contacts[contain].hasOwnProperty(prop))
        return contacts[contain][prop];
      else
        return "No such property";
    else
      return "No such contact";
  }  
  else if(firstName == "Sherlock"){
    contain = 2;
    if(contacts[contain].firstName == firstName)
      if(contacts[contain].hasOwnProperty(prop))
        return contacts[contain][prop];
      else
        return "No such property";
    else
      return "No such contact";
  }
  else if(firstName == "Kristian"){
    contain = 3;
    if(contacts[contain].firstName == firstName)
      if(contacts[contain].hasOwnProperty(prop))
        return contacts[contain][prop];
      else
        return "No such property";
    else
      return "No such contact";

  }
  else
    return "No such contact";


// Only change code above this line
}

// Change these values to test your function
lookUpProfile("Akira", "lastName");

Answer 1

You have very repetitive code. This can be optimized. I'm not sure whether your function name lookUpProfile is the correct one, as you actually look up a property of a Contact and not its whole profile. But if the task is to look up a certain property of a Contact you can simplify the code to this:

function lookUpProfile(firstName, prop) {
    for (let contact of contacts) {  
        if (contact.firstName === firstName) {
            return contact[prop];
        }
    }
    return false;
}

How it works

It loops through all contacts:

for (let contact of contacts) {

It tests whether the firstName matches:

if (contact.firstName === firstName) {

In case a match is found it returns the requested property or undefined:

return contact[prop];

In case no match is found it returns false:

return false;

What it returns

This function will have a mixed return value. The code that is calling the function can now deal with the result. It will return one of the following:

• false if no Contact with the requested firstName exists
• undefined if a Contact matches but the requested property doesn't exists
• string|array if a match was found and the property exists

So all those calls will work:

console.log(
    lookUpProfile(),
    lookUpProfile('A'),
    lookUpProfile('Sherlock'),
    lookUpProfile('Sherlock', 'number'),
    lookUpProfile('Kristian', 'likes')
);

The return values are:

false false undefined 0487345643 Array [ "Javascript", "Gaming", "Foxes" ]

What the code doesn't do:

It doesn't check whether there's a choice for Contacts, i.e. if more than one Contact with that name exists. It will always exit at the first match.

jsFiddle Demo

Try before buy

---

Update "No such property"

Regarding the OP's comment about a different return value, I would suggest keeping the code as is and let other parts worry about a concrete message:

var value = lookUpProfile('Sherlock', 'random');

if ('undefined' === typeof value) {
    console.log('No such property');
};

If your task is to include that text into the function you can replace this line:

return contact[prop];

with:

return 'undefined' === typeof contact[prop] ? 'No such property' : contact[prop];

This is a lot harder to handle, as the string "No such property" could be an actual value of a property.

Answer 2

// Setup
const contacts = [
  {
    firstName: "Akira",
    lastName: "Laine",
    number: "0543236543",
    likes: ["Pizza", "Coding", "Brownie Points"],
  },
  {
    firstName: "Harry",
    lastName: "Potter",
    number: "0994372684",
    likes: ["Hogwarts", "Magic", "Hagrid"],
  },
  {
    firstName: "Sherlock",
    lastName: "Holmes",
    number: "0487345643",
    likes: ["Intriguing Cases", "Violin"],
  },
  {
    firstName: "Kristian",
    lastName: "Vos",
    number: "unknown",
    likes: ["JavaScript", "Gaming", "Foxes"],
  },
];

function lookUpProfile(name, prop) {
  // Only change code below this line
  for (let i = 0; i < contacts.length; i++ ) {
    if (contacts[i]['firstName'] === name && contacts[i].hasOwnProperty(prop)) {
      return contacts[i][prop];
    }
    if (contacts[i]['firstName'] === name && !(contacts[i].hasOwnProperty(prop))) {
      return 'No such property';
    }
  }
  return 'No such contact';
  // Only change code above this line
}

console.log(lookUpProfile("Kristian", "lastName"));
console.log(lookUpProfile("Sherlock", "likes"));
console.log(lookUpProfile("Harry", "likes"));
console.log(lookUpProfile("Bob", "number"));
console.log(lookUpProfile("Bob", "potato"));
console.log(lookUpProfile("Akira", "address"));
console.log(lookUpProfile("Akira", "likes"));