reverse()
ES3+Reverses an array in place and returns the reference to the same array.
Syntax
array.reverse()Return Value
The reversed array
Examples
const numbers = [1, 2, 3, 4, 5];
numbers.reverse();
console.log(numbers);📌 When to Use
Use reverse() when you need to reverse the order of array elements in place. Common uses include reversing sorted data, displaying items in newest-first order, or implementing stack-like LIFO behavior.
⚠️ Common Mistakes
Forgetting that reverse() modifies the original array in place
Using reverse() in React/Vue state directly - this mutates state unexpectedly
Chaining reverse() incorrectly: arr.reverse().filter() modifies arr first
✅ Best Practices
For immutable reverse, use toReversed() (ES2023) or [...arr].reverse()
To reverse a string: str.split("").reverse().join("")
Copy first if you need the original: const reversed = [...arr].reverse()
⚡ Performance Notes
reverse() is O(n/2) as it swaps elements from both ends toward the middle. It's an in-place operation, so no additional memory is allocated. Creating a copy with spread first makes the overall operation O(n).
🌍 Real World Example
Displaying Messages in Chronological Order
Reverse an array of messages sorted oldest-first to display newest first
// Messages from API are sorted oldest first
const messages = await fetchMessages(); // [{id: 1, time: '10:00'}, ...]
// Display newest first without modifying original
const displayMessages = [...messages].reverse();
// For React state (always copy first)
setMessages(prev => [...prev].reverse());
// Reverse a string
const original = 'Hello';
const reversed = original.split('').reverse().join('');
// reversed: 'olleH'