What are some use cases for rest and spread operators in JavaScript?

What are some use cases for rest and spread operators in JavaScript?

Rest and spread operators are powerful tools in JavaScript. The rest operator allows you to collect multiple elements into an array, while the spread operator lets you expand an array into individual elements. They can be used in function arguments, array manipulation, and object cloning.

Can you give me an example of using the rest operator?

Sure! Here's an example:

function sum(...numbers) {
  return numbers.reduce((acc, num) => acc + num, 0);
}
console.log(sum(1, 2, 3, 4)); // Outputs: 10

In this case, the ...numbers syntax collects all arguments into an array.

What about the spread operator? How is it used?

The spread operator can be used to expand an array into individual elements. For example:

const arr1 = [1, 2, 3];
const arr2 = [4, 5, ...arr1];
console.log(arr2); // Outputs: [4, 5, 1, 2, 3]

Here, ...arr1 spreads the elements of arr1 into arr2.

Are there any other interesting use cases?

Absolutely! You can use the spread operator for merging objects, like this:

const obj1 = { a: 1, b: 2 };
const obj2 = { b: 3, c: 4 };
const merged = { ...obj1, ...obj2 };
console.log(merged); // Outputs: { a: 1, b: 3, c: 4 }

This merges obj1 and obj2, with properties from obj2 overwriting those in obj1.