This content originally appeared on DEV Community and was authored by Hacker Pro
Hey devs! 
Whether you’re just starting with JavaScript or already knee-deep in frameworks, it’s always a good idea to keep your core JS skills sharp.
Here are 10 simple but powerful JavaScript tips, each with an example you can copy-paste and play with right away.
Let’s dive in! 
1. map() vs forEach() — Know When to Use
const numbers = [1, 2, 3, 4];
const mapped = numbers.map(num => num * 2); // returns new array
const forEachResult = [];
numbers.forEach(num => forEachResult.push(num * 2));
console.log(mapped); // [2, 4, 6, 8]
console.log(forEachResult); // [2, 4, 6, 8]
Tip: Use map() when you want to return a new array. Use forEach() when you just want to run side effects (like logging or pushing).
2. Optional Chaining Saves You from Errors
const user = {
name: 'John',
address: {
city: 'Dhaka'
}
};
console.log(user?.address?.city); // 'Dhaka'
console.log(user?.contact?.email); // undefined (no crash!)
Tip: Use optional chaining (?.) to safely access deeply nested properties without throwing runtime errors.
3. Nullish Coalescing vs Logical OR
const count = 0;
const result1 = count || 10; // 10 ❌
const result2 = count ?? 10; // 0 ✅
console.log(result1); // 10
console.log(result2); // 0
Tip: Use ?? when you want to preserve valid falsy values like 0, false, or “”.
4. Clean Object Access with Destructuring
const person = {
name: "Alice",
age: 28,
location: "Chittagong"
};
const { name, age } = person;
console.log(name); // Alice
console.log(age); // 28
Tip: Destructuring makes your code more concise and readable, especially when dealing with props or API responses.
5. setTimeout Inside Loops — Use let, Not var
for (var i = 0; i < 3; i++) {
setTimeout(() => console.log(i), 1000); // 3 3 3 ❌
}
for (let i = 0; i < 3; i++) {
setTimeout(() => console.log(i), 1000); // 0 1 2 ✅
}
Tip: Use let in loops with async logic. var is function-scoped, let is block-scoped.
6. Convert String to Number Quickly
const str = "42";
console.log(+str); // 42
console.log(Number(str)); // 42
console.log(parseInt(str)); // 42
Tip: The unary + operator is a fast and clean way to convert strings to numbers.
7. Copy Objects Without Side Effects
const original = { name: "Dev", age: 25 };
const copy = { ...original };
copy.name = "Code";
console.log(original.name); // Dev
console.log(copy.name); // Code
Tip: Use the spread operator { …obj } to create shallow copies and avoid unintended mutations.
8. Filter Arrays Like a Pro
const numbers = [1, 2, 3, 4, 5, 6];
const even = numbers.filter(n => n % 2 === 0);
console.log(even); // [2, 4, 6]
Tip: .filter() returns a new array containing only the values that match your condition.
9. Check If an Object Is Empty
const obj = {};
const isEmpty = Object.keys(obj).length === 0;
console.log(isEmpty); // true
Tip: A simple and effective way to validate API responses, form data, and configs.
10. Default Parameters in Functions
function greet(name = "Developer") {
return `Hello, ${name}!`;
}
console.log(greet()); // Hello, Developer!
console.log(greet("Shaun")); // Hello, Shaun!
Tip: Default parameters help you write cleaner functions without repetitive if checks.
These small, clean, and efficient JavaScript tips can have a big impact on your daily workflow.
They help write bug-free, readable, and maintainable code — whether you’re building frontend UIs or backend services.
Got a favorite JS tip?
Let me know in the comments or share this with your fellow devs! 
This content originally appeared on DEV Community and was authored by Hacker Pro