[SOLVED] Question on Basic JavaScript: Record Collection Challenge

JavaScript
1

Hi everyone,

I am struggling with understanding the basic code solution. My thinking is I’m not connecting something from a previous lesson and would like to get a ‘play by play’ explanation of the solution. I commented my understanding using // :

Your code so far


// Setup
var collection = {
    "2548": {
      "album": "Slippery When Wet",
      "artist": "Bon Jovi",
      "tracks": [ 
        "Let It Rock", 
        "You Give Love a Bad Name" 
      ]
    },
    "2468": {
      "album": "1999",
      "artist": "Prince",
      "tracks": [ 
        "1999", 
        "Little Red Corvette" 
      ]
    },
    "1245": {
      "artist": "Robert Palmer",
      "tracks": [ ]
    },
    "5439": {
      "album": "ABBA Gold"
    }
};
// Keep a copy of the collection for tests
var collectionCopy = JSON.parse(JSON.stringify(collection));

// Only change code below this line
function updateRecords(id, prop, value) {
        // First checks if PROP is equal to TRACKS AND if VALUE isn't a blank string
	if (prop === "tracks" && value != "") {  
                // If prop is TRACKS and VALUE isn't empty ("")          
		if(collection[id][prop]) {
                  // Pushes the value onto the end of the album's existing tracks array
                  collection[id][prop].push(value);
    }
    // If prop is "tracks" but the album doesn't have a "tracks" property, creates an empty array before adding the new value to the album's corresponding property
    else {
      collection[id][prop]=[value];
    }
  }
  // Checks if VALUE equals empty string ??
  else if (value !== "") {
    collection[id][prop] = value;
  } 
  else {
    // If both these checks fail (meaning value must be an empty string). Then the key (prop) is removed from the object.
    delete collection [id][prop];
  }

  return collection;
}

// Alter values below to test your code
updateRecords(5439, "artist", "ABBA");

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-javascript/record-collection

2

I don’t remember all the requirements of this challenge, but I think that you might be missing the case where collection[id] doesn’t exist?

Also, you have a syntax error here in the form of an extra space:

  delete collection [id][prop];
3

Is this understandable?

function updateRecords(id, prop, value) {
  if (prop === "tracks" && value !== "") { // first it checks if prop is tracks and value is not an empty string
   if(collection[id][prop]) { // if "collection[id][prop] is truthy (as in, it exists) push the new value into the array
    collection[id][prop].push(value);
   }
   else { // if that property doesn't exist then create an array for that property with "value" inside of it
    collection[id][prop]=[value];
   }
  } else if (value !== "") { // if it is not tracks and value is not an empty string, set that value to that property
    collection[id][prop] = value;
  } else { // else if it is not tracks and value is an empty string, delete that property
    delete collection[id][prop];
  }

  return collection;
}
2 Likes
4

Yes!! Thank you so much! :smile:

5

Your code has been blurred out to avoid spoiling a full working solution for other campers who may not yet want to see a complete solution. In the future, if you post a full passing solution to a challenge and have questions about it, please surround it with [spoiler] and [/spoiler] tags on the line above and below your solution code.

Thank you.

6

Sorry, as the OP was talking about the code from the hints section (and posted that) didn’t think of blurring it out

7

No worries. Just something we try to do.

8

@ilenia Could you please explain the id, prop, and value references? I don’t know how they connect to the rest of the array, and connect to the function when they are mentioned the other times. I know the for example in console.log that when it’s called outside of the function at the end then those can give values to the corresponding function values. I don’t get how that works here. I saw another solution use id, prop, and value and I don’t know where those are coming from.

9

Those are the parameters of the function,

function updateRecords(id, prop, value) { /*...*/ };

which are filled with values when the function is called with arguments:

updateRecords(5439, "artist", "ABBA");

do you know what function paramenters and function arguments are?

so id, prop and value are variables that hold a value, what to do with this values is explained in the challenge description

1 Like