Repeat even number inside the same array - JavaScript

We are required to write a JavaScript function that should repeat the even number inside the same array.

Therefore, for example given the following array −

const arr = [1, 2, 5, 6, 8];

We should get the output −

const output = [1, 2, 2, 5, 6, 6, 8, 8];

Example

Following is the code −

const arr = [1, 2, 5, 6, 8];
const repeatEvenNumbers = arr => {
   let end = arr.length -1;
   for(let i = end; i > 0; i--){
      if(arr[i] % 2 === 0){
         arr.splice(i, 0, arr[i]);
      };
   };
   return arr;
};
console.log(repeatEvenNumbers(arr));

Output

This will produce the following output on console −

[
    1, 2, 2, 5,
    6, 6, 8, 8
]