Code Smell 71 — Magic Floats Disguised as Decimals

Don’t trust numbers on immature languages like JavaScript.

Photo by Stephen Radford on Unsplash

Problems

• Principle of Least Surprise Violation
• Accidental Complexity
• Wrong decimal representations.

Solutions

1. Choose Mature Languages.

2. Represent Decimals with Decimals.

Sample Code

Wrong

Right

Detection

Since this is a language feature, it is difficult to detect. We can ask our linters to prevent us from manipulating numbers this way.

Tags

• JavaScript
• Premature Optimization

Conclusion

My first programming language was Commodore's basic back in 1985.

I was very surprised to discover that 1+1+1 was not always 3. Then they introduced integer types.

JavaScript is 30 years younger, and it has the same immaturity problems.

Relations

Code Smell 69 — Big Bang (JavaScript Ridiculous Castings)

More info

Here is the technical (and accidental) explanation.

Blogs - Pankaj Tanwar - Software Engineer

Please, don’t argue telling this is fine and expected since this is the binary representation.

These numbers are decimal, we should represent them as decimals.

If you think representing them as floats is a great performance improvement, you are wrong.

Premature optimization is the root of all evil.

List of languages with this defect:

Floating Point Math

The purpose of computing is insight, not numbers.

Richard Hamming

Software Engineering Great Quotes

This article is part of the CodeSmell Series.

How to Find the Stinky parts of your Code