How to Sort an Array in JavaScript

Use sort() when you need to reorder array items alphabetically, numerically, or by object properties. The key is choosing the right compare function so the result matches the order you actually want.

What you’ll build or solve

You’ll learn how to sort an array in JavaScript using sort(). You’ll also know how to sort strings, numbers, and arrays of objects safely.

When this approach works best

This approach is the right choice when the same data needs to be displayed in a predictable order.

Common real-world scenarios include:

• Product price sorting
• Alphabetical name lists
• Leaderboards
• Date ordering
• Priority task views

This is a bad idea when the original array order must stay untouched. In that case, copy the array before sorting.

Prerequisites

You only need:

• A JavaScript file or browser console
• A basic array
• Basic JavaScript array knowledge

Step-by-step instructions

Step 1: Use sort() with the right compare function

For strings, sort() works directly.

const names = ["Mia", "Alex", "Jordan"];

names.sort();

console.log(names);

For numbers, always add a compare function.

const scores = [45, 72, 8, 100];

scores.sort((a, b) => a - b);

console.log(scores);

For descending order, flip the comparison.

scores.sort((a, b) => b - a);

What to look for:

• String sorting works by default
• Number sorting needs a compare function
• a - b sorts ascending
• b - a sorts descending
• sort() changes the original array

Examples you can copy

Alphabetical names

const students = ["Taylor", "Alex", "Morgan"];

students.sort();

Low to high prices

const prices = [29, 9, 49, 19];

prices.sort((a, b) => a - b);

Sort by object property

const users = [
  { name: "Alex", age: 30 },
  { name: "Mia", age: 24 }
];

users.sort((a, b) => a.age - b.age);

Common mistakes and how to fix them

Mistake 1: Sorting numbers without a compare function

What the reader might do:

const numbers = [100, 8, 20];

numbers.sort();

Why it breaks: JavaScript converts values to strings, so "100" comes before "8".

Corrected approach:

numbers.sort((a, b) => a - b);

Mistake 2: Expecting the original array to stay unchanged

What the reader might do:

scores.sort((a, b) => a - b);
console.log(scores);

Why it breaks: sort() mutates the original array.

Corrected approach:

const sortedScores = [...scores].sort((a, b) => a - b);

Mistake 3: Returning true or false in the compare function

What the reader might do:

numbers.sort((a, b) => a > b);

Why it breaks: the compare function should return a negative, zero, or positive number.

Corrected approach:

numbers.sort((a, b) => a - b);

Troubleshooting

If numbers sort strangely, add a compare function.

If the original order changes unexpectedly, copy the array first.

If object sorting fails, verify the property name inside the callback.

If descending order looks wrong, reverse the subtraction order.

Quick recap

• Use sort() to reorder arrays
• Strings sort directly
• Numbers need a compare function
• sort() mutates the original array
• Copy first if the original order matters