What does the spread operator (...) do in JavaScript?

The spread operator (...) in JavaScript is used to expand or spread elements of an iterable (like an array or a string) into individual elements. It can be used in various contexts, such as:

1. Array Literals: To create a new array by combining existing arrays or adding new elements.

   const array1 = [1, 2, 3];
   const array2 = [4, 5, 6];
   const combinedArray = [...array1, ...array2]; // [1, 2, 3, 4, 5, 6]

2. Function Arguments: To pass elements of an array as individual arguments to a function.

   const numbers = [1, 2, 3];
   const sum = (a, b, c) => a + b + c;
   console.log(sum(...numbers)); // 6

3. Object Literals: To create a new object by copying properties from an existing object.

   const obj1 = { a: 1, b: 2 };
   const obj2 = { ...obj1, c: 3 }; // { a: 1, b: 2, c: 3 }

4. String Expansion: To convert a string into an array of characters.

   const str = "hello";
   const chars = [...str]; // ['h', 'e', 'l', 'l', 'o']

The spread operator is a powerful feature that simplifies code and enhances readability.