TL;DR: Don't use ternaries for code execution. You should read them as a math formula.

Problems

• Difficult to read

• Low Reuse

• Low Testability

Solutions

1. Extract the method guards

Refactorings

Context

When a ternary condition is used in code that contains multiple functions, it can be challenging to determine which function is being affected by the condition.

This can make it harder to identify and fix bugs, as well as to understand how the code works in general.

Sample Code

Wrong

const invoice = isCreditCard ? 
  prepareInvoice();
  fillItems();
  validateCreditCard();
  addCreditCardTax();
  fillCustomerDataWithCreditCard();
  createCreditCardInvoice() 
:
  prepareInvoice();
  fillItems();
  addCashDiscount();
  createCashInvoice();

// The intermediate results are not considered
// The value of the invoice is the result of
// The last execution

Right

const invoice = isCreditCard ? 
                    createCreditCardInvoice() :
                    createCashInvoice();

// or better 

if (isCreditCard) {
  const invoice = createCreditCardInvoice();
} else {
  const invoice = createCashInvoice();
}

// Even better with polymorphism
paymentMethod.createInvoice();

Detection

[X] Automatic

Linters can detect large code blocks

Tags

• Bloaters

Conclusion

No matter where you have long lines of code, you can always refactor into higher-level functional and shorter methods.

Relations

More Info

Disclaimer

Code Smells are my opinion.

Credits

Photo by Jens Lelie on Unsplash

Thanks, Cory

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The programs that live best and longest are those with short functions. You learn just how valuable all those little functions are. All of the payoffs of indirection—explanation, sharing, and choosing—are supported by small functions.

Martin Fowler

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This article is part of the CodeSmell Series.