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Hello everyone,
So far I tried for a couple of hours this exercise but I didn’t understand it, neither the exercise nor the solution given in the “get a hint” page then I’m a bit frustrated.
the exercise says:
Blockquote
Basic JavaScript: Record Collection
You are given a JSON object representing a part of your musical album collection. Each album has several properties and a unique id number as its key. Not all albums have complete information.
Write a function which takes an album’s id
(like 2548
), a property prop
(like "artist"
or "tracks"
), and a value
(like "Addicted to Love"
) to modify the data in this collection.
If prop
isn’t "tracks"
and value
isn’t empty ( ""
), update or set the value
for that record album’s property.
Your function must always return the entire collection object.
There are several rules for handling incomplete data:
If prop
is "tracks"
but the album doesn’t have a "tracks"
property, create an empty array before adding the new value to the album’s corresponding property.
If prop
is "tracks"
and value
isn’t empty ( ""
), push the value
onto the end of the album’s existing tracks
array.
If value
is empty ( ""
), delete the given prop
property from the album.
Hints
Use bracket notation
when accessing object properties with variables.
Push is an array method you can read about on Mozilla Developer Network.
You may refer back to Manipulating Complex Objects Introducing JavaScript Object Notation (JSON) for a refresher.
Blockquote
My questions are:
-
Why is used directly prop === “tracks” in the first if?.. I though since “tracks” is part of the array then the code should specify where “tracks” is … I don’t know , something like collection[id][tracks] or something.
-
Why in the else if the value is not in ? I though the idea was to get the array of value.
The code is bellow the questions.
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) {
if(prop === "tracks" && value!==""){
if (collection[id][prop]){
collection[id][prop].push(value);
} else
{
collection[id][prop] = [value];
}
}
else if (value !== "") {
collection[id][prop] = value;
}
else {
delete collection[id][prop];
}
return collection;
}
// Alter values below to test your code
updateRecords(5439, "artist", "ABBA");
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.
Link to the challenge: