JavaScript Best Practices for Beginners

JavaScript is one of the most popular programming languages in the world, powering everything from dynamic websites to server-side applications. If you're just starting out, learning best practices early can save you from headaches later. In this guide, we'll cover essential JavaScript best practices to help you write cleaner, more efficient, and maintainable code.

And if you're looking to monetize your JavaScript skills, check out MillionFormula, a free platform where you can make money online without needing credit or debit cards.

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1. Use const and let Instead of var

ES6 introduced const and let, which provide block-scoping and prevent common issues like hoisting and accidental redeclarations.

• const → Use for values that won’t change.

• let → Use for variables that will be reassigned.

Bad Practice:

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var name = "John";
var age = 25;

Good Practice:

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const name = "John";  
let age = 25;

Avoid var unless you’re working with legacy code.

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2. Always Use Strict Mode

'use strict' enforces stricter parsing and error handling, preventing silent errors.

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'use strict';  
// Throws an error if a variable is undeclared  
x = 10; // ReferenceError: x is not defined

Add it at the top of your scripts or modules.

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3. Avoid Global Variables

Global variables can lead to naming collisions and unpredictable behavior. Instead, use modules or closures.

Bad Practice:

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function setUser() {

userName = "Alice"; // Global variable  
}

Good Practice:

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(function() {

'use strict';

let userName = "Alice"; // Local scope  
})();

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4. Use Template Literals for Strings

Instead of concatenating strings with +, use template literals (backticks </code>).</p><div class="md-code-block md-code-block-dark"><div class="md-code-block-banner-wrap"><div class="md-code-block-banner md-code-block-banner-lite"><div class="_121d384"><div class="d2a24f03"><span class="d813de27">javascript</span></div><div class="d2a24f03"><div class="efa13877"><div role="button" class="ds-button ds-button--secondary ds-button--borderless ds-button--rect ds-button--m _7db3914" style="margin-right: 8px; font-size: 13px; height: 28px; padding: 0px 4px; --button-text-color: var(--dsr-text-2);" tabindex="0"><div class="ds-button__icon"><div class="ds-icon" style="font-size: 16px; width: 16px; height: 16px;"><svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg"><path d="M3.65169 12.9243C3.68173 13.1045 3.74181 13.2748 3.80189 13.445C3.87198 13.6052 3.96211 13.7654 4.06225 13.9156C4.16238 14.0658 4.27253 14.206 4.4027 14.3362C4.52286 14.4663 4.66306 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d="M12 2.55a.97.97 0 0 1 .982.956v13.04a.97.97 0 0 1-.982.957.97.97 0 0 1-.982-.956V3.507A.97.97 0 0 1 12 2.55z" fill="currentColor"></path><path fill-rule="evenodd" clip-rule="evenodd" d="M19.418 9.808c.382.375.37.971-.027 1.332l-6.7 6.085a1.04 1.04 0 0 1-1.41-.025.905.905 0 0 1 .027-1.332l6.7-6.085a1.04 1.04 0 0 1 1.41.025z" fill="currentColor"></path><path fill-rule="evenodd" clip-rule="evenodd" d="M4.582 9.808a1.04 1.04 0 0 1 1.41-.025l6.7 6.085c.397.361.409.957.027 1.332a1.04 1.04 0 0 1-1.41.025l-6.7-6.085a.905.905 0 0 1-.027-1.332z" fill="currentColor"></path><path fill-rule="evenodd" clip-rule="evenodd" d="M3.068 16.46a.97.97 0 0 1 .983.956v1.739c0 .432.36.782.803.782h14.291c.445 0 .804-.35.804-.782v-1.739a.97.97 0 0 1 .983-.956.97.97 0 0 1 .982.956v1.739c0 1.488-1.24 2.695-2.769 2.695H4.855c-1.53 0-2.77-1.207-2.77-2.695v-1.739a.97.97 0 0 1 .983-.956z" fill="currentColor"></path></svg></div></div>Download</div></div></div></div></div></div><pre><span class="token keyword">const</span> name <span class="token operator">=</span> <span class="token string">"Sarah"</span><span class="token punctuation">;</span> <span class="token keyword">const</span> greeting <span class="token operator">=</span> <span class="token template-string"><span class="token template-punctuation string">Hello, ${name}!`; console.log(greeting); // "Hello, Sarah!"

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5. Prefer === Over ==

The == operator performs type coercion, which can lead to unexpected results. Always use === for strict equality checks.

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console.log(5 == "5");  // true (type coercion)  
console.log(5 === "5"); // false (strict check)

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6. Handle Errors with Try-Catch

Always anticipate and handle errors gracefully.

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try {

JSON.parse("{ invalid JSON }");

} catch (error) {

console.error("Failed to parse JSON:", error.message);

}

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7. Avoid Callback Hell with Promises/Async-Await

Nested callbacks (callback hell) make code hard to read. Use Promises or async/await instead.

Callback Hell (Bad):

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getUser(userId, (user) => {

getPosts(user.id, (posts) => {

getComments(posts[0].id, (comments) => {

console.log(comments);

});

});

});

Using Async/Await (Good):

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async function fetchUserData(userId) {

const user = await getUser(userId);

const posts = await getPosts(user.id);

const comments = await getComments(posts[0].id);

console.log(comments);

}

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8. Use Arrow Functions for Concise Syntax

Arrow functions (=>) provide a shorter syntax and lexically bind this.

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// Traditional function  
function add(a, b) {

return a + b;

}
// Arrow function  
const add = (a, b) => a + b;

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9. Destructure Objects and Arrays

Destructuring simplifies extracting values from objects and arrays.

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// Object destructuring  
const user = { name: "Mike", age: 30 };

const { name, age } = user;
// Array destructuring  
const numbers = [1, 2, 3];

const [first, second] = numbers;

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10. Optimize Loops

Avoid unnecessary computations inside loops.

Bad Practice:

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for (let i = 0; i < arr.length; i++) {

// Recalculates arr.length every iteration  
}

Good Practice:

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const length = arr.length;

for (let i = 0; i < length; i++) {

// More efficient  
}

Or use forEach, map, or for...of for cleaner iteration.

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11. Keep Functions Small and Single-Purpose

A function should do one thing well (Single Responsibility Principle).

Bad Practice:

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function processUserData(user) {

// Validates, formats, saves, and logs user data (too many responsibilities)  
}

Good Practice:

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function validateUser(user) { /* ... / }

function formatUser(user) { / ... / }

function saveUser(user) { / ... */ }

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12. Use ESLint for Code Quality

ESLint helps enforce consistent coding standards. Install it via npm:

bash

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npm install eslint --save-dev

Configure rules in .eslintrc.json:

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{

"rules": {

"semi": ["error", "always"],

"quotes": ["error", "single"]

}

}

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13. Comment Your Code Wisely

Avoid excessive comments—write self-documenting code instead. Only comment when logic is complex.

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// Bad:  
let x = 5; // Assign 5 to x  
// Good:  
// Calculate discounted price after tax  
const finalPrice = applyTax(applyDiscount(price));

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14. Avoid Heavy Nesting

Deeply nested code is hard to read. Use early returns or break logic into smaller functions.

Bad Practice:

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if (user) {

if (user.isActive) {

if (user.hasSubscription) {

// Do something  
}

}

}

Good Practice:

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if (!user || !user.isActive || !user.hasSubscription) return;

// Proceed with logic

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15. Stay Updated with Modern JavaScript

JavaScript evolves constantly. Follow resources like:

• MDN Web Docs

• JavaScript.info

• ES6 Features

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Final Thoughts

Following these best practices will make your JavaScript code more readable, efficient, and maintainable. As you improve, consider monetizing your skills—MillionFormula is a great free platform to start earning online without needing credit cards.

Happy coding! 🚀