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Home/Blog/Programming/10 JavaScript tips: Best practices to simplify your code

10 JavaScript tips: Best practices to simplify your code

Q: What are the three basic rules for JavaScript?

The three key rules of JavaScript are as follows: - Declare variables before use to avoid global scope issues. - JavaScript is case-sensitive (e.g., `myVariable` ≠ `myvariable`). - Lexical scoping: Inner functions can access outer variables, but not vice versa.

Q: What is the best practice for declaring a variable in JavaScript?

The best practice is to use `let` and `const` instead of `var`. The `const` function should be used for values that don’t change, ensuring immutability, while `let` is ideal for variables that need reassignment. Avoid declaring variables globally to prevent conflicts and memory leaks. Always initialize variables when declaring them to avoid `undefined` errors and improve code clarity.

14 min read

May 30, 2025

content

10 JavaScript best practices

1. Declare and initialize variables at the start

Why is this important?

Best practice implementation

2. Write modular and reusable functions for better code efficiency

Why is this important?

Best practice implementation

3. Eliminate duplicate code for cleaner and more efficient JavaScript

Why is this important?

Best practice implementation

4. Use meaningful comments to improve code readability

Why is this important?

Best practice implementation

Best practices for writing comments

5. Enable strict mode to catch hidden JavaScript errors

Why is this important?

Best practice implementation

How to use the strict mode

6. Optimize DOM manipulations for better performance

Why is this important?

Best practice implementation

Best practices for efficient DOM manipulation

7. Use recursion wisely to avoid performance issues

Why is this important?

Best practice implementation

8. Minimize global variables to prevent conflicts and improve performance

Why is this important?

Best practice implementation

9. Use shorthand notation for cleaner and more efficient object literals

Why is this important?

Best practice implementation

Shorthand notation for arrays

10. Use .includes() for efficient existence checks in arrays

Why is this important?

Best practice implementation

When to use .indexOf()

Conclusion

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Key takeaways:

JavaScript hoists variable declarations, but initializing them early in the process prevents unexpected behavior.
Excessive use of global variables can lead to naming conflicts and memory inefficiencies, impacting performance in large applications.
Recursion can cause stack overflow errors if not properly managed with base cases.
Strict mode ('use strict') prevents silent errors and enforces safer coding practices.
Repeated DOM access is inefficient—caching elements improves performance significantly.

Imagine this: you take over a JavaScript project from a teammate. You’re hoping for clean, clear code—but instead, it’s a mess of confusing variables and hard-to-follow logic. Frustrating, right?

Now think about the opposite.

What if your code is the one everyone enjoys working with—simple, clear, and easy to follow?

Writing clean, readable JavaScript makes a big difference. It’s not just a nice-to-have—it can completely change how smoothly things run.

So, how do you take your JavaScript from good to great?

In this blog, we’ll cover 10 simple practices that make your code cleaner, easier to read, and more enjoyable to work with. Ready to level up your JavaScript skills? Let’s get started!

10 JavaScript best practices#

JavaScript powers everything from dynamic websites to complex web applications — but with great flexibility comes great responsibility. No matter where you are in your JavaScript journey, the way you write code can either set you up for long-term success or leave you tangled in technical debt.

Learn JavaScript

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JavaScript is a versatile language essential for web development, working alongside HTML and CSS to build both simple and complex web applications. This course offers a comprehensive introduction to JavaScript for beginners, starting with fundamental concepts like problem-solving and simple JavaScript programs. Through interactive exercises, challenges, and quizzes, learners will master control structures, loops, strings, arrays, and functions. By the end of this course, you'll have solid problem-solving skills, a deep understanding of JavaScript programming, and practical experience in writing clean, efficient code. This knowledge will prepare you for a successful career as a JavaScript developer and significantly enhance your employability in the tech industry.

8hrs

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4 Challenges

4 Quizzes

These 10 best practices will help you craft code that’s functional, future-proof, and readable.

Declare and initialize variables at the start.
Write modular and reusable functions for better code efficiency.
Eliminate duplicate code for cleaner and more efficient JavaScript.
Use meaningful comments to improve code readability.
Enable strict mode to catch hidden JavaScript errors.
Optimize DOM manipulations for better performance.
Use recursion wisely to avoid performance issues.
Minimize global variables to prevent conflicts and improve performance.
Use shorthand notation for cleaner and more efficient object literals.
Use .includes() for efficient existence checks in arrays.

1. Declare and initialize variables at the start#

Organization is key to writing clean, efficient, and readable code in JavaScript. One of the most fundamental best practices is declaring and initializing variables at the top of your script or function.

Why is this important?#

Enhances readability: Developers can quickly locate all variables, making debugging and maintenance easier.
Prevents hoisting issues: JavaScript hoists variable declarations, but keeping them at the top eliminates unexpected behavior.
Improves maintainability: It’s easier to tweak or modify variable names and values in one place.
Reduces undefined errors: Initializing variables when they’re declared prevents accidental usage of undefined values.

Best practice implementation#

Always declare variables at the beginning of a function or script and initialize them immediately to avoid undefined values.

Not recommended: Scattered declarations

Pro tip: Use let and const instead of var:

The var keyword has function scope and can lead to unexpected bugs due to hoisting. Instead, prefer let for reassignable values and const for constants.
// Use let for reassignable variables, const for constants
let x = 5;
const PI = 3.14;

2. Write modular and reusable functions for better code efficiency#

In JavaScript, functions should be concise and focused on a single responsibility. Writing monolithic functions that handle multiple tasks hurts readability and makes maintenance and debugging more difficult.

A better approach is to break down large functions into smaller, modular functions, each designed to perform one specific task. Let’s look at how modular functions improve readability and maintainability.

Why is this important?#

Improves readability: A function with a clear, descriptive name that handles one job is easier to understand.
Enhances reusability: Smaller functions can be reused across different projects without modification.
Simplifies debugging and maintenance: When a function does just one thing, it’s easier to locate and fix errors.
Encourages code scalability: Modifying a function that is too broad may cause unintended side effects. Keeping functions specialized prevents this issue.

Best practice implementation#

Not recommended: One function doing too much

Pro tip: Use descriptive function names

A function’s name should clearly describe its purpose without requiring users to read through the code. If you have to explain what a function does, it probably needs refactoring.
function fetchUserData(userId) {
    // Retrieves user data from the database
}

function formatCurrency(amount) {
    // Converts a number to a currency format
}

Learn to Code: Javascript for Absolute Beginners

8hrs

Beginner

4 Challenges

4 Quizzes

3. Eliminate duplicate code for cleaner and more efficient JavaScript#

Duplicate code is one of the biggest culprits behind messy, inefficient, and hard-to-maintain JavaScript. Repeating the same logic multiple times clutters your code, makes debugging difficult, and increases the likelihood of errors.

The solution? Identify repetitive patterns and extract them into reusable functions.

Why is this important?#

Reduces visual clutter: Keeps your code clean and organized.
Improves maintainability: Changes must only be made in one place instead of multiple locations.
Enhances debugging: Fixing bugs becomes easier since a single function controls all instances of an operation.
Boosts reusability: Encapsulating logic into functions allows reuse throughout the project.

Best practice implementation#

Not recommended: Duplicate code

Pro tip: Use higher-order functions for more efficiency

If you have multiple values to process, consider using array methods like map(), which eliminates redundancy further:
let numbers = [5, 6];

let doubledNumbers = numbers.map(num => num * 2);

console.log(doubledNumbers); // Output: [10, 12]
This approach scales better when dealing with multiple variables

4. Use meaningful comments to improve code readability#

Code should be self-explanatory, but even the clearest code can benefit from well-placed comments. Thoughtful comments help developers understand your logic, catch potential mistakes, and improve collaboration.

Many teams follow the “leave one comment per function” rule to ensure clarity without clutter. If you’re ever unsure whether to add a comment, just do it! Unnecessary comments can be removed later, but missing comments can slow down debugging and maintenance.

Why is this important?#

Improves readability: Helps others (and future you) understand the purpose of code at a glance.
Aids debugging: Clarifies intended functionality, making it easier to spot logic errors.
Enhances collaboration: Team members can quickly understand and modify the code.
Acts as documentation: Provides context when returning to code after weeks or months.

Best practice implementation#

Not recommended: No comments

5. Enable strict mode to catch hidden JavaScript errors#

JavaScript is a forgiving language, often letting silent errors slip through without throwing explicit warnings. While this flexibility helps get code to run, it can lead to unexpected behavior, hidden bugs, and security risks.

The solution? Enable strict mode ('use strict';). This mode enforces stricter parsing and error handling, helping you catch mistakes early before they cause bigger problems.

Why is this important?#

Catches silent errors: JavaScript may ignore or resolve certain mistakes ambiguously without strict mode.
Prevents undeclared variables: Assigning values to undeclared variables throws an error instead of creating global variables accidentally.
Disallows dangerous syntax: Stops unsafe operations, like duplicate parameter names or writing to read-only properties.
Improves performance: Strict mode enforces better coding practices, reducing the risk of silent errors and unintended global variables.

Best practice implementation#

Not recommended: Without strict mode, silent errors may occur

Pro tip: Strict mode also prevents common errors

Prevents accidental global variables:
'use strict';
myVar = 5; // Uncaught ReferenceError: myVar is not defined
Disallows duplicate function parameters:
'use strict';
function sum(a, a) {  // SyntaxError: Duplicate parameter name not allowed
    return a + a;
}
Restricts eval() and argument usage:
'use strict';
eval("var x = 2;");
console.log(x); // ReferenceError: x is not defined

6. Optimize DOM manipulations for better performance#

The Document Object Model (DOM) is a fundamental part of web development, allowing JavaScript to dynamically interact with and update HTML elements. However, repeatedly accessing the DOM can cause:

Performance slowdowns due to frequent rerenders
Visual clutter in the code
Unnecessary processing overhead

A better approach is to cache your DOM elements in variables and access them only once, reducing redundant lookups and improving efficiency.

Why is this important?#

Boosts performance: Reduces unnecessary DOM traversals, making scripts run faster.
Enhances readability: Code looks cleaner and more structured.
Simplifies maintenance: DOM references are stored in variables, making updates easier.
Minimizes repetitive queries: Instead of searching the DOM multiple times, you retrieve elements from a variable.

Best practice implementation#

Not recommended: Repeated DOM access

Pro tip: Use $ prefix for jQuery variables

A common convention in jQuery-based projects is to prefix cached DOM elements with $, making them easily recognizable.
var $header = $("#header"); // Clearer indication of a jQuery object
This small convention improves code readability and maintainability.

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284 Playgrounds

27 Quizzes

7. Use recursion wisely to avoid performance issues#

Recursion is powerful, but excessive nesting can hurt readability and performance. Deeply nested recursive functions are difficult to follow, debug, and maintain.

Why is this important?#

Improves readability: Minimizes complex nesting that’s hard to trace.
Enhances debugging: Shallow functions are easier to troubleshoot.
Prevents stack overflow errors: Overuse of recursion can cause excessive memory consumption.
Optimizes performance: In many cases, iteration is a better alternative.

Best practice implementation#

Not recommended: Too many nested recursive calls

Pro tip: Consider iteration over recursion

If recursion isn’t necessary, convert it into a loop to avoid excessive function calls.
function factorial(n) {
    let result = 1;
    for (let i = 2; i <= n; i++) {
        result *= i;
    }
    return result;
}
This is more memory-efficient than recursive factorial implementations.

8. Minimize global variables to prevent conflicts and improve performance#

In JavaScript, variable scope determines where a variable can be accessed. Global variables—which exist outside of functions—should be avoided because they:

Increase the risk of accidental overwrites.
Cause naming conflicts in large applications.
Consume memory unnecessarily since they persist until the page is closed.

Instead, use local variables within functions or block scopes to keep your code modular, efficient, and error-free.

Why is this important?#

Prevents conflicts: Global variables can unintentionally overwrite built-in JavaScript objects.
Improves performance: Global variables persist in memory, while local variables are released after use.
Enhances maintainability: Keeping variables local makes debugging easier and reduces side effects.
Encourages modular code: Using function or block-scoped variables keeps code structured and scalable.

Best practice implementation#

Not recommended: Global variable pollution

Pro tip: Use IIFE (Immediately invoked function expressions) to maintain local scope

If you must use variables globally, encapsulate them in an IIFE to prevent conflicts.
(function () {
    let myVar = "I am safely scoped"; // Encapsulated within function
    console.log(myVar);
})();
This keeps variables isolated from the global scope.

9. Use shorthand notation for cleaner and more efficient object literals#

Shorthand notation improves readability, efficiency, and maintainability when defining objects or arrays in JavaScript. Instead of setting properties or array elements line by line, declare them directly within an object or array literal.

This reduces clutter, makes code easier to scan, and minimizes redundancy, especially as objects and arrays become more complex.

Why is this important?#

Saves line space: Objects and arrays are more compact and visually cleaner.
Enhances readability: Team members can quickly understand object structures.
Improves maintainability: Easier to modify and update object properties.
Reduces boilerplate code: Eliminates repetitive assignments and increases efficiency.

Best practice implementation#

Not recommended: Longhand object creation

Pro tip: Use shorthand property names for objects

If the variable name and object property name are the same, you can use ES6 shorthand property names:
let brand = "Dell";
let price = 1200;

// Shorthand property assignment
let computer = { brand, price };

console.log(computer); // { brand: "Dell", price: 1200 }
Saves even more space by omitting redundant key-value pairs.

10. Use .includes() for efficient existence checks in arrays#

Checking whether a value exists in an array is a common operation in JavaScript. Instead of loops or manual searches, the .includes() method provides a cleaner, faster, and more readable solution by returning a boolean (true or false).

Why is this important?#

Simplifies code: Avoids complex loops and conditional checks.
Enhances readability: Clearly expresses the intent of checking for existence.
Improves performance: Optimized for quick lookups, especially for small arrays.
Works with both strings and arrays: A Versatile method for various use cases.

Best practice implementation#

Not recommended: Using indexOf() for existence check

Pro tip: Use .some() for more complex conditions

If checking custom conditions, Array.some() is a great alternative:
const users = [
    { name: "Alice", role: "admin" },
    { name: "Bob", role: "user" }
];

const isAdminPresent = users.some(user => user.role === "admin");

console.log(isAdminPresent); // true
The .some() method checks object properties inside an array.

Conclusion#

Mastering JavaScript goes beyond making code work—it’s about writing clean, efficient, and maintainable code that others can easily read and understand. Following these best practices will improve your coding skills, enhance collaboration, reduce debugging time, and boost overall performance.

Each technique contributes to a more structured and scalable JavaScript codebase, from declaring variables initially and eliminating duplicate code to optimizing DOM manipulations and using shorthand notations.

Ready to take your JavaScript skills to the next level? Start implementing these best practices today and see the difference!

To explore more JavaScript tips and hands-on learning, check out Educative’s interactive course and sharpen your skills with real-world coding challenges!

Frequently Asked Questions

How do you simplify JavaScript code?

Simplify JavaScript by writing modular functions, reducing redundancy, and leveraging ES6+ features like destructuring, arrow functions, and template literals. Use shorthand syntax, cache DOM elements, and enable strict mode ('use strict') to catch errors and enhance reliability.

What are the three basic rules for JavaScript?

The three key rules of JavaScript are as follows:

Declare variables before use to avoid global scope issues.
JavaScript is case-sensitive (e.g., myVariable ≠ myvariable).
Lexical scoping: Inner functions can access outer variables, but not vice versa.

How can I make JavaScript better?

Minimize global variables, optimize loops, and handle errors with try...catch. Write readable, well-commented code and avoid deep nesting. Use array methods like map() and filter() for cleaner scripts. Stay updated with ES6+ for optimized, future-proof code.

What is the best practice for declaring a variable in JavaScript?

The best practice is to use let and const instead of var. The const function should be used for values that don’t change, ensuring immutability, while let is ideal for variables that need reassignment. Avoid declaring variables globally to prevent conflicts and memory leaks. Always initialize variables when declaring them to avoid undefined errors and improve code clarity.

Written By:

Ryan Thelin

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10 JavaScript tips: Best practices to simplify your code

10 JavaScript best practices#

1. Declare and initialize variables at the start#

Why is this important?#

Best practice implementation#

2. Write modular and reusable functions for better code efficiency#

Why is this important?#

Best practice implementation#

3. Eliminate duplicate code for cleaner and more efficient JavaScript#

Why is this important?#

Best practice implementation#

4. Use meaningful comments to improve code readability#

Why is this important?#

Best practice implementation#

Best practices for writing comments#

5. Enable strict mode to catch hidden JavaScript errors#

Why is this important?#

Best practice implementation#

How to use the strict mode#

6. Optimize DOM manipulations for better performance#

Why is this important?#

Best practice implementation#

Best practices for efficient DOM manipulation#

7. Use recursion wisely to avoid performance issues#

Why is this important?#

Best practice implementation#

8. Minimize global variables to prevent conflicts and improve performance#

Why is this important?#

Best practice implementation#

9. Use shorthand notation for cleaner and more efficient object literals#

Why is this important?#

Best practice implementation#

Shorthand notation for arrays#

10. Use .includes() for efficient existence checks in arrays#

Why is this important?#

Best practice implementation#

When to use .indexOf()#

Conclusion#

Frequently Asked Questions

How do you simplify JavaScript code?

What are the three basic rules for JavaScript?

How can I make JavaScript better?

What is the best practice for declaring a variable in JavaScript?