If I see a Variable that doesn't change. I call that variable a constant If I see a Variable that doesn't change. I call that variable a constant TL;DR: Be explicit on what mutates and what doesn't. TL;DR: Be explicit on what mutates and what doesn't. Problems Addressed 😔 Mutability
Code Optimization Mutability Mutability Code Optimization Related Code Smells 💨 https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxii?embedable=true https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxii?embedable=true https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxvi?embedable=true https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxvi?embedable=true https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxiv?embedable=true https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxiv?embedable=true Context 💬 Variables that never change their value are not really variables. They’re constants pretending to be mutable state. When we declare something as a variable, we tell the reader (and the compiler) to expect change. If that change never happens, we’re sending misleading signals about what the code actually does. Converting these to constants shrinks the state space a developer must track. A constant signals that a value won’t change, preventing accidental reassignments and letting the compiler optimize better. It’s honest: if something shouldn’t mutate, don’t let it. Steps 👣 Find the scope of the variable
Define a constant with the same scope
Replace the variable Find the scope of the variable Define a constant with the same scope Replace the variable Sample Code 💻 Before 🚨 let lightSpeed = 300000;
var gravity = 9.8;

// 1. Find the scope of the variable
// 2. Define a constant with the same scope
// 3. Replace the variable let lightSpeed = 300000;
var gravity = 9.8;

// 1. Find the scope of the variable
// 2. Define a constant with the same scope
// 3. Replace the variable After 👉 const lightSpeed = 300000;
const gravity = 9.8;

// 1. Find the scope of the variable
// 2. Define a constant with the same scope
// 3. Replace the variable 

// If the object is compound, 
// we might need Object.freeze(gravity); const lightSpeed = 300000;
const gravity = 9.8;

// 1. Find the scope of the variable
// 2. Define a constant with the same scope
// 3. Replace the variable 

// If the object is compound, 
// we might need Object.freeze(gravity); Type 📝 [X] Automatic IDEs can check if a variable is written but never updated. Safety 🛡️ This is a safe refactoring. Why is the Code Better? ✨ Code is more compact and declares intent clearly. Take it further with language-specific operators like const, final, or let. const final let The scope becomes obvious at a glance. How Does it Improve the Bijection? 🗺️ This refactoring improves bijection by making it clear what mutates and what doesn't. bijection In the real world, most values don't change. They're constants. Declaring them as variables creates coupling between what we're thinking and how we wrote it. coupling Constants remove that gap and align the code with the actual domain. Tags 🏷️ Mutability Mutability Level 🔋 [X] Beginner Related Refactorings 🔄 https://hackernoon.com/improving-the-code-one-line-at-a-time?embedable=true https://hackernoon.com/improving-the-code-one-line-at-a-time?embedable=true Refactor with AI 🤖 Suggested Prompt: 1. Find the scope of the variable.2. Define a constant with the same scope.3. Replace the variable Suggested Prompt: 1. Find the scope of the variable.2. Define a constant with the same scope.3. Replace the variable Without Proper Instructions 📵 ChatGPT
Claude
Perplexity
Copilot
You
Gemini
DeepSeek
Meta AI
Grok
Qwen ChatGPT ChatGPT Claude Claude Perplexity Perplexity Copilot Copilot You You Gemini Gemini DeepSeek DeepSeek Meta AI Meta AI Grok Grok Qwen Qwen With Specific Instructions 👩‍🏫 ChatGPT
Claude
Perplexity
Copilot
You
Gemini
DeepSeek
Meta AI
Grok
Qwen ChatGPT ChatGPT Claude Claude Perplexity Perplexity Copilot Copilot You You Gemini Gemini DeepSeek DeepSeek Meta AI Meta AI Grok Grok Qwen Qwen See also 📚 https://hackernoon.com/is-it-crystal-clear-for-everybody-that-a-date-should-not-mutate-wuoy3z03?embedable=true https://hackernoon.com/is-it-crystal-clear-for-everybody-that-a-date-should-not-mutate-wuoy3z03?embedable=true This article is part of the Refactoring Series https://maximilianocontieri.com/how-to-improve-your-code-with-easy-refactorings?embedable=true https://maximilianocontieri.com/how-to-improve-your-code-with-easy-refactorings?embedable=true https://maximilianocontieri.com/how-to-improve-your-code-with-easy-refactorings https://maximilianocontieri.com/how-to-improve-your-code-with-easy-refactorings

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Refactoring 008 - Variables That Never Change Should Be Constants

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