JavaScript(JS) Spread Operator

The spread operator (...) in JavaScript is a syntax for spreading the elements of an iterable (like an array or a string) into individual elements. It can be used in a variety of contexts to make working with iterable data structures more flexible and expressive.

Here are some examples of using the spread operator in JavaScript:

1. Concatenating arrays:

let arr1 = [1, 2, 3];
let arr2 = [4, 5, 6];
let arr3 = [...arr1, ...arr2];

console.log(arr3); // output: [1, 2, 3, 4, 5, 6]

In this example, the spread operator is used to concatenate the elements of arr1 and arr2 into a new array arr3.

2. Copying arrays:

let arr1 = [1, 2, 3];
let arr2 = [...arr1];

console.log(arr2); // output: [1, 2, 3]

In this example, the spread operator is used to create a copy of arr1 in a new array arr2.

3. Passing arguments to a function:

function sum(x, y, z) {
  return x + y + z;
}

let numbers = [1, 2, 3];
let result = sum(...numbers);

console.log(result); // output: 6

In this example, the spread operator is used to pass the elements of the numbers array as separate arguments to the sum function.

4. Merging objects:

let obj1 = {a: 1, b: 2};
let obj2 = {c: 3, d: 4};
let obj3 = {...obj1, ...obj2};

console.log(obj3); // output: {a: 1, b: 2, c: 3, d: 4}

In this example, the spread operator is used to merge the properties of obj1 and obj2 into a new object obj3.