Question

In the case that each method and variable will only be used once, which is the more correct convention?

Creating as many variables as necessary:

var x = GmailApp.getInboxUnreadCount();
var email = GmailApp.getInboxThreads (0, x);

Composing the code in one line:

var email = GmailApp.getInboxThreads (0, GmailApp.getInboxUnreadCount());

Answer 1

The latter, within reason. But this is largely a matter of style in the simple cases.

Meaning that if you have a function call that takes 10 arguments, and each of those arguments comes from a large function call itself, dont do this. Think of who gets your code base afterward.

“Is this line of code readable using less local variables? Or do I need to break it up to better illustrate what the line is doing?” is the question you should ask yourself. And in this case, the latter is totally readable.

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In fact, I would argue the first example is less readable due to a useless local variable name x. If instead that were named better, it might be a more viable option.

var unreadCount = GmailApp.getInboxUnreadCount();
var email = GmailApp.getInboxThreads (0, unreadCount);

This is better, but still pretty unnecessary in this very simple case.