Record collection (super confused)

[NikIvan]

@NKos

Also, can we use the return command after every if/else if statement and if not, why are we putting it at the end of the code?

Basically what you are asking about is called “Early return pattern” and yes, you can do that. This approach could be better in some situations. Let’s try to rewrite this function with it (keeping same functionality):

function updateRecords(records, id, prop, value) {
  if (prop !== "tracks" && value !== "") {
    records[id][prop] = value;
    return records;
  }
  
  if (prop === "tracks" && records[id].hasOwnProperty("tracks")=== false) {
    records[id][prop] = [value];
    return records;
  }
  
  if (prop === "tracks" && value !== "") {
    records[id][prop].push(value);
    return records;
  }

  if (value === "") {
    delete records[id][prop];
    return records;
  }

  return records;
}

As you can see above using this pattern for current situation is not the best idea because it adds repetitiveness which breaks DRY principle.

To sum up, any pattern has it’s own up- and downsides and should be used mindfully.

For more detailed explanation please look here:

The Return Early Pattern Explained with JavaScript Examples

The return early pattern in JavaScript is a simple way to reduce the number of else statements within a function body to zero. There are many reasons to prefer this pattern over using else statements. Reducing the total amount of code on the page Reduce line length by reducing logical complexity Improve Readability The essence of the return early pattern is to replace the need for else conditionals in JavaScript functions by using the return keyword in the body of the if statement. …

Return Early Pattern