Retrieving property from Javascript Object

Question

For the below code. The following return the correct results:

lookUpProfile("Bob", "number"); // returns 'No such contact'
lookUpProfile("Akira", "address"); // return 'No such property'

However, for the following it doesn't return the expected result.

lookupProfile("Kristian", "lastName"); // should return 'Vos'
lookupProfile("Sherlock", "likes"); // should return ["Intriguing Cases", "Violin"]

Thank you.

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

  for (var i = 0; i < contacts.length; i++) {
    if (contacts[i][firstName] === firstName) {
      if (contacts[i][prop] === prop) {
        return contacts[i][prop];
      } else {
        return "No such property";
      }
    } else {
      return "No such contact";
    } 
  }
// Only change code above this line
}

lookupProfile("Kristian", "lastName"); must be lookUpProfile("Kristian", "lastName"); — Amit Garg
– Amit Garg, Commented Jun 12, 2017 at 8:30

Weedoze · Accepted Answer · 2017-06-12 11:59:10Z

You are trying to access the property like this contacts[i].prop

prop is a variable thus you need to use the brackets notation contacts[i][prop]

Another way of doing this :

You can use Array#find() to get the contact with the first name.

find() will return undefined if it doesn't find a contact. They you can access the property and see if it returns undefined or not

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) {
  const contact = contacts.find(c=>c.firstName === firstName);
  if(!contact) return "No such contact";
  const propValue = contact[prop];
  if(!propValue) return "No such property";
  return propValue;
}

console.log(lookUpProfile("Bob", "number")); // returns 'No such contact'
console.log(lookUpProfile("Akira", "address")); // return 'No such property'
console.log(lookUpProfile("Kristian", "lastName")); // should return 'Vos'
console.log(lookUpProfile("Sherlock", "likes")); // should return ["Intriguing Cases", "Violin"]

And with a one-liner return

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) {
  const contact = contacts.find(c=>c.firstName === firstName);
  return contact ? contact[prop] ? contact[prop] : "No such property" : "No such contact";
}

console.log(lookUpProfile("Bob", "number")); // returns 'No such contact'
console.log(lookUpProfile("Akira", "address")); // return 'No such property'
console.log(lookUpProfile("Kristian", "lastName")); // should return 'Vos'
console.log(lookUpProfile("Sherlock", "likes")); // should return ["Intriguing Cases", "Violin"]

And using a for-loop

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){
  for(let i=0; i<contacts.length; i++){
    if(contacts[i].firstName === firstName){
      if(contacts[i].hasOwnProperty(prop)){
        return contacts[i][prop];
      }else{
        return "No such property";
      }
    }
  }
  return "No such contact";
}

console.log(lookUpProfile("Bob", "number")); // returns 'No such contact'
console.log(lookUpProfile("Akira", "address")); // return 'No such property'
console.log(lookUpProfile("Kristian", "lastName")); // should return 'Vos'
console.log(lookUpProfile("Sherlock", "likes")); // should return ["Intriguing Cases", "Violin"]

Weedoze. Thank you for such a good solution. Is there a way to do it using for noobie syntax such as: function lookUpProfile(firstName, prop){ // Only change code below this line for (var i = 0; i < contacts.length; i++) { if (contacts[i][firstName] === firstName) { if (contacts[i][prop] === prop) { return contacts[i][prop]; } else { return "No such property"; } } else { return "No such contact"; } } // Only change code above this line }
@martinbshp No problem - You should check the built-in functions :) They can be very useful - map(), find(), filter(), reduce(),...

Egor Stambakio · Accepted Answer · 2017-06-12 08:27:30Z

1

Correct code for getting your prop:

return contacts[i][prop]

When you do contacts[i].prop it's looking for {'prop': ...}

Corresponding docs: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_Accessors

answered Jun 12, 2017 at 8:27

Egor Stambakio

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Comments

Paul Roub · Accepted Answer · 2017-06-12 15:15:20Z

0

for (var key in contacts) {
  //You can loop through the contacts object
  var obj = contacts[key];//get the object
}

edited Jun 12, 2017 at 15:15

Paul Roub

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answered Jun 12, 2017 at 8:30

GaAd

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