Steer Clear of Magic Numbering: Why You Should Avoid It in Your Code

In the programming world, there is a term that raises eyebrows and evokes a sense of caution: magic numbering. It refers to using unexplained numerical values directly in source code without providing clear context or named constants. Although this anti-pattern has existed since the early days of programming, it continues to plague codebases and hinder code maintainability. In this blog post, we will explore magic numbering, why it is a bad programming practice, and how we can avoid its pitfalls in JavaScript.

Understanding Magic Numbers

A magic number is a unique value that appears multiple times in code, often lacking any explanation of its meaning or significance. It violates the fundamental principle of clean code by obscuring the developer’s intent and making the code more difficult to comprehend. The use of magic numbers in programming has been frowned upon since the early days of COBOL, FORTRAN, and PL/1.

In the following example, the number 1000 is used as a magic number to define the upper limit of the random number generation.

function generateRandomNumber() {
  return Math.floor(Math.random() * 1000); // Generating a random number up to 1000
}

The Consequences of Magic Numbering

The consequences of using unknown magic numbers are far-reaching. First and foremost, it obscures the developer’s intent in choosing that particular value, leading to confusion and potential bugs. Moreover, updating these magic numbers throughout the codebase becomes daunting, making the code more fragile and error-prone. As the codebase grows, the lack of clear context and explanation can challenge new developers joining the project.

To overcome the pitfalls of magic numbering, it is essential to adhere to best practices and replace magic numbers with named constants or explanatory variables. This practice aligns with the Single Point of Truth (SPOT) concept, where constants are defined in one place and referenced throughout the codebase. It allows for more accessible updates and maintenance, as changes can be made in a centralised location.

Incorporating Constants in JavaScript

In JavaScript, the use of constants can be achieved through various mechanisms. The language provides the const keyword to declare variables that are meant to be constant. By defining constants for significant numbers, we can improve code readability and maintainability.

By taking our previous example, it would be more appropriate to define the 1000 value as a constant, such as const MAX_RANDOM_NUMBER = 1000, to make the code more understandable and allow for easy adjustment.

function generateRandomNumber() {
  const MAX_RANDOM_NUMBER = 1000;
  return Math.floor(Math.random() * MAX_RANDOM_NUMBER); // Generating a random number up to MAX_RANDOM_NUMBER
}

Magic numbering is a notorious programming practice that should be avoided to maintain clean, readable, and maintainable code. By replacing magic numbers with named constants, we can provide clarity, enhance code understanding, and make future updates more manageable. As JavaScript developers, embracing best practices and striving for code free from the “magic” that can cause confusion and hinder progress is crucial.

In conclusion, it is best practice to give them meaningful names when it comes to magic numbers. This makes your code more transparent and accessible to both present and future developers.