Update Record Collection

javascript/FreeCodeCamps/Basic JavaScript/Record Collection.md

@@ -1,26 +1,16 @@
 # Record Collection
 
-You are given a `JSON` object representing (a small part of) your record collection.
-Each album is identified by a unique `id` number (`its key`) and has
-several properties. Not all albums have complete information.
-
-Write a function which takes an `id`, a property (prop), and a value.
-
-For the given `id` in collection:
-
-If prop does not contain the key `tracks`, then update or set
-the value for that incomplete prop.
-
-If prop does not contain the key `tracks` before you update
-it, create an empty array before pushing a track to it.
-
-If prop does contain the key `tracks` and its value is non-blank,
-then push the value onto the end of its existing tracks array.
-
-If value is blank, delete that prop.
-
-Always return the entire collection object.
-
+You are given an object literal representing a part of your musical album collection. Each album has a unique id number as its key and several other properties. Not all albums have complete information. <br>
+<br>
+You start with an `updateRecords` function that takes an object literal, `records`, containing the musical album collection, an `id`, a `prop` (like `artist` or `tracks`), and a `value`. Complete the function using the rules below to modify the object passed to the function.<br>
+<br>
+Your function must always return the entire record collection object.<br>
+- If `prop` isn't `tracks` and value isn't an empty string, update or set that album's `prop` to `value`.
+- If `prop` is` tracks` but the album doesn't have a `tracks` property, create an empty array and add `value` to it.
+- If `prop` is `tracks` and `value` isn't an empty string, add `value` to the end of the album's existing `tracks` array.
+- If `value` is an empty string, delete the given `prop` property from the album.
+Note: A copy of the `recordCollection` object is used for the tests.<br>
+<br>
 ## Hints
  - Use `bracket notation` when accessing object properties with variables.
 
@@ -32,97 +22,72 @@ You may refer back to Manipulating Complex ObjectsIntroducing JavaScript Object
 
 ```javascript
 // 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"
-    }
+const recordCollection = {
+  2548: {
+    albumTitle: 'Slippery When Wet',
+    artist: 'Bon Jovi',
+    tracks: ['Let It Rock', 'You Give Love a Bad Name']
+  },
+  2468: {
+    albumTitle: '1999',
+    artist: 'Prince',
+    tracks: ['1999', 'Little Red Corvette']
+  },
+  1245: {
+    artist: 'Robert Palmer',
+    tracks: []
+  },
+  5439: {
+    albumTitle: '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) {
-
-
-  return collection;
+function updateRecords(records, id, prop, value) {
+  return records;
 }
 
-// Alter values below to test your code
-updateRecords(5439, "artist", "ABBA");
+updateRecords(recordCollection, 5439, 'artist', 'ABBA');
 ```
 
 ### Answers
 
 ```javascript
 // 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"
-    }
+const recordCollection = {
+  2548: {
+    albumTitle: 'Slippery When Wet',
+    artist: 'Bon Jovi',
+    tracks: ['Let It Rock', 'You Give Love a Bad Name']
+  },
+  2468: {
+    albumTitle: '1999',
+    artist: 'Prince',
+    tracks: ['1999', 'Little Red Corvette']
+  },
+  1245: {
+    artist: 'Robert Palmer',
+    tracks: []
+  },
+  5439: {
+    albumTitle: '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) {
+function updateRecords(records, id, prop, value) {
 
-  if (value === '') {
-    delete collection[id][prop]; // If the value is empty remove the prop
-  } else if (prop !== "tracks") {
-    collection[id][prop] = value;
+ if (value === '') {
+    delete records[id][prop];
+  } else if (prop === 'tracks') {
+    records[id][prop] = records[id][prop] || []; // this is called shortcircuit evaluation, see below for explanation
+    records[id][prop].push(value);
   } else {
-    if (!collection[id].hasOwnProperty('tracks')) {
-      collection[id].tracks = [];
-      collection[id].tracks.push(value);
-    } else {
-      collection[id].tracks.push(value);
-    }
+    records[id][prop] = value;
   }
-  return collection;
+  return records;
 }
-
-// Alter values below to test your code
-updateRecords(2468, "tracks", "Free");
+updateRecords(recordCollection, 5439, 'artist', 'ABBA');
 ```
 
 ### Thinking
@@ -131,4 +96,4 @@ updateRecords(2468, "tracks", "Free");
 2. If the prop is not tracks it's easy to add the value to this prop
 3. Here we need to find if the object have a property tracks if not we create
 this prop with a empty array and we push it the value. I use `.hasOwnProperty` for
-doing this.
+doing this.