Sorting Custom Objects

The sort() method sorts array elements in place and returns the sorted array. By default, it sorts elements as strings. To sort numbers or objects, you must provide a compare function.

Compare Function

The compare function takes two arguments a and b and returns:

• < 0 if a should come before b
• 0 if a and b are equal
• > 0 if a should come after b

Code Example

// Sorting numbers correctly
const numbers = [10, 5, 40, 25];
numbers.sort((a, b) => a - b);
console.log(numbers); // [5, 10, 25, 40]

// Sorting objects by property
const users = [
  { name: "Alice", age: 30 },
  { name: "Bob", age: 25 },
  { name: "Charlie", age: 35 },
];

// Sort by age ascending
users.sort((a, b) => a.age - b.age);
console.log(users);
// [{ name: "Bob", age: 25 }, { name: "Alice", age: 30 }, { name: "Charlie", age: 35 }]

// Sort by name alphabetically
users.sort((a, b) => a.name.localeCompare(b.name));
console.log(users);
// [{ name: "Alice", ... }, { name: "Bob", ... }, { name: "Charlie", ... }]

// Multi-level sorting: by age, then by name
const users2 = [
  { name: "Alice", age: 30 },
  { name: "Bob", age: 25 },
  { name: "Charlie", age: 30 },
];
users2.sort((a, b) => {
  if (a.age !== b.age) return a.age - b.age;
  return a.name.localeCompare(b.name);
});
console.log(users2);
// Bob (25), Alice (30), Charlie (30)