Javascript working with arrays of objects

Working with arrays of objects in JavaScript is common when managing lists of data, like users, products, or any structured information.

1. Filtering - filter()

Use filter() to create a new array with objects that meet a specific condition.

const users = [
  { name: "Alice", age: 25 },
  { name: "Bob", age: 30 },
  { name: "Charlie", age: 25 },
];

// Filter users by age
const age25Users = users.filter(user => user.age === 25);
console.log(age25Users); // [{ name: "Alice", age: 25 }, { name: "Charlie", age: 25 }]

2. Finding - find()

The find() method returns the first object that matches a condition.

const user = users.find(user => user.name === "Bob");
console.log(user); // { name: "Bob", age: 30 }

3. Mapping - map()

Use map() to create a new array by transforming each object.

const names = users.map(user => user.name);
console.log(names); // ["Alice", "Bob", "Charlie"]

4. Sorting - sort()

The sort() method allows sorting the array based on object properties.

const sortedByAge = [...users].sort((a, b) => a.age - b.age);
console.log(sortedByAge);

5. Reducing - reduce()

The reduce() method accumulates values in the array, useful for summing or aggregating data.

const totalAge = users.reduce((acc, user) => acc + user.age, 0);
console.log(totalAge); // 80

6. Checking Conditions - some() and every()

some() checks if at least one element matches a condition.
every() checks if all elements match a condition.

const hasYoungUser = users.some(user => user.age < 30);
console.log(hasYoungUser); // true

const allUsersAreAdults = users.every(user => user.age >= 18);
console.log(allUsersAreAdults); // true

7. Grouping by Property

Grouping can be done using reduce() for complex structures.

const groupedByAge = users.reduce((group, user) => {
  const age = user.age;
  if (!group[age]) group[age] = [];
  group[age].push(user);
  return group;
}, {});

console.log(groupedByAge);
/* Output:
{
  "25": [{ name: "Alice", age: 25 }, { name: "Charlie", age: 25 }],
  "30": [{ name: "Bob", age: 30 }]
}
*/

These methods make managing and manipulating arrays of objects in JavaScript both efficient and straightforward.

Utility Types: Learn TypeScript’s built-in utility types like Partial, Pick, Omit, and Record

What is Javascript?