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Code Smell 145 - Short Circuit Hack

Maxi Contieri on June 30, 2022

Don't use boolean evaluation as a readability shortcut TL;DR: Don't use Boolean comparison for side effect functions. Problems Read...

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Ingo Steinke, web developer • Jun 30 '22

What about optional chaining? Which of course only works with functions designed to be chained, like user?.isValid()?.logUserIn();

Ben Sinclair • Jun 30 '22

I'd use that for finding a deep value but not performing an action:

if (user?.foo?.bar) {
  user.login();
  // or...
  logUserIn(user);
  // or whatever
}

Also, the implication in your example is that isValid() returns a user object when that's not obvious - it looks like it should be a boolean.

Felicia Ann Kelley • Jul 4 '22

It has to be a boolean, boolean is how the data is first made.

Kentaro Tanaka • Jul 19 '24

The condition essentially evaluates to a boolean value, determining whether the nested property user.foo.bar exists and is truthy.

I am also engineer. Can we discuss more details?

Maxi Contieri • Jun 30 '22 • Edited

Null is the worst code smell

And optional chaining, IMHO hids this antipattern.
I've written a smell on optional chaining. I will publish it in the following weeks

hackernoon.com/null-the-billion-do...

And optional chaining is another code smell

Code Smell 149 - Optional Chaining

Maxi Contieri ・ Jul 16 ・ 2 min read

#javascript #webdev #beginners #programming

Lars Ejaas • Jul 2 '22

But we are not always writing the data or code with null ourselves.

One example: Auto-generated types made with GraphQL Code Generator.
We still need to be able to handle null.
Null does indeed make sense if you do not know if data will return empty.

Omar Benmegdoul • Jul 3 '22 • Edited

Why is this a problem specifically before a side-effect?

Something like myFunc?.() will force people to pause. On the other hand short-circuits are a common pattern when setting default values or optionally rendering React components. People are used to reading them in other contexts, often with function calls on the right, so why do they become less readable in this one?