freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/basic-javascript/profile-lookup/index.md

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Profile Lookup

Profile Lookup

Remember to use Read-Search-Ask if you get stuck. Try to pair program and write your own code

Problem Explanation:

We have an array of objects representing different people in our contacts lists.

A lookUpProfile() function that takes firstName and a property (prop) as arguments has been pre-written for you.

The function should check if firstName is an actual contact's firstName and the given property (prop) is a property of that contact.

If both are true, then return the value of that property.

If firstName does not correspond to any contacts then return No such contact.

If prop does not correspond to any valid properties then return No such property.

• Change the code below // Only change code below this line and up to // Only change code above this line.
• Ensure that you are editing the inside of the lookUpProfile() function.
  • This function includes two parameters, firstName and prop.
• The function should look through the contacts list for the given firstName parameter.
  • If there is a match found, the function should then look for the given prop parameter.
  • If both firstName and the associated prop are found, you should return the value of the prop.
  • If firstName is found and no associated prop is found, you should return No such property.
• If firstName isn't found anywhere, you should return No such contact.

Hint: 1

Use a for loop to cycle through the contacts list.

try to solve the problem now

Hint: 2

Use a nested if statement to first check if the firstName matches, and then checks if the prop matches.

try to solve the problem now

Hint: 3

Leave your return "No such contact" out of the for loop as a final catch-all.

try to solve the problem now

Spoiler Alert!

Solution ahead!

Basic Code Solution:

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

Code Explanation:

• The for loop runs, starting at the first object in the contacts list.
• If the firstName parameter passed into the function matches the value of the "firstName" key in the first object, the if statement passes.
• Then, we use .hasOwnProperty() method (checks if there's a given property and returns a boolean) with prop as an argument. If it's true, the value of prop is returned.
  • If the second if statement fails, No such property is returned.
• If the first if statement fails, the for loop continues on to the next object in the contacts list.
• If the firstName parameter isn't matched by the final contacts object, the for loop exits and No such contact is returned.

Example Run

• lookUpProfile("Akira","likes"); runs.
• "Akira" is matched to the "firstName" key in the first object, so the if statement returns true.
• "likes" is found within the first object, so the second if statement returns true.
• The value of "likes" is returned - "Pizza", "Coding", "Brownie Points".

Alternative code solution:

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

· Run code at repl.it.

Code explanation

This works as the last example but uses the in operator to look for prop instead of the hasOwnProperty() method.

Resources

• "Iterate with JavaScript For Loops" - fCC's challenge
• "Object.prototype.hasOwnProperty()" - MDN JavaScript reference
• "in operator" - MDN JavaScript reference