Code Smell 86 — Mutable Const Arrays

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Const declares something to be constant. Can it mutate?

TL;DR: Don’t rely on languages cheating about directives.

Problems

• Unexpected side effects
• Accidental complexity

Solutions

1. Use better languages
2. Use spread operator

Sample Code

Wrong

Right

Detection

Since this is a “language feature”, we can explicitly forbid it.

Tags

• Mutability
• JavaScript

Conclusion

We should always favour immutability on our designs and take extra care with side effects.

More Info

• The evil power of mutants

Credits

Thank you,Oliver Jumpertz for this tip.

Correctness is clearly the prime quality. If a system does not do what it is supposed to do, then everything else about it matters little.

Bertrand Meyer

Software Engineering Great Quotes

This article is part of the CodeSmell Series.

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