What are the benefits of using spread syntax and how is it different from rest syntax?

In JavaScript, the spread syntax and rest syntax are both used to manipulate arrays and objects.

The spread syntax allows you to expand an array or an object into its individual elements or properties. It is represented by three dots (...). For example, you can use the spread syntax to merge two arrays into a new one, like this:

let arr1 = [1, 2, 3];
let arr2 = [4, 5, 6];
let newArr = [...arr1, ...arr2]; 
console.log(newArr) // [1, 2, 3, 4, 5, 6]

You can also use the spread syntax to make a shallow copy of an array or an object, like this:

let originalArr = [1, 2, 3];
let copyArr = [...originalArr];
console.log(originalArr === copyArr) //false

The rest syntax, on the other hand, allows you to gather multiple elements or properties and put them into an array. It is represented by three dots (...). It is mostly used to gather all the remaining arguments passed to a function that is not destructured. For example, you can use the rest syntax to gather all the remaining arguments passed to a function, like this:

function sum(a, b, ...args) {
  let total = a + b;
  for (let arg of args) {
    total += arg;
  }
  return total;
}
console.log(sum(1, 2, 3, 4, 5)) // 15

In summary, the spread syntax allows you to expand an array or an object into its individual elements or properties, while the rest syntax allows you to gather multiple elements or properties and put them into an array. The spread syntax is mainly used to merge and copy arrays or objects, while the rest syntax is mainly used to gather all the remaining arguments passed to a function that is not destructured.