Adding new value to existing array in javascript

In JavaScript, you can add a new value to an existing array using several methods. Here are a few ways to do it:

1. Using the push() method:

   let arr = [1, 2, 3];
   arr.push(4); // [1, 2, 3, 4]

   The push() method adds a new element to the end of the array.

2. Using the concat() method:

   let arr = [1, 2, 3];
   arr = arr.concat([4]); // [1, 2, 3, 4]

   The concat() method returns a new array with the elements of the original array and the new elements.

3. Using the splice() method:

   let arr = [1, 2, 3];
   arr.splice(2, 0, 4); // [1, 2, 4, 3]

   The splice() method adds a new element at a specific position (in this case, the third position) and shifts the existing elements to the right.

4. Using the unshift() method:

   let arr = [1, 2, 3];
   arr.unshift(4); // [4, 1, 2, 3]

   The unshift() method adds a new element to the beginning of the array.

5. Using the spread operator (...):

   let arr = [1, 2, 3];
   arr = [...arr, 4]; // [1, 2, 3, 4]

   The spread operator creates a new array with the elements of the original array and the new elements.

Note that some of these methods modify the original array, while others return a new array. Be careful when using these methods to ensure you're working with the desired array.