JSFiddle - React, Tailwind, and code Playground

JavaScript

var arr = [2, 3, 5, 8, 8, 2, 2];
var val = 2

function s(arr, val) {
	let idx1 = null;
  let idx2 = null;
	let remainders = [];
	for (let i = 0; i < arr.length; i++) {
  		if (arr[i] === val) {
      	if (idx1 !== null) {
        	idx1 = i;
        } else {
        	idx2 = i;
        }
      } else {
      	remainders.push(arr[i]);
      }
  }
  
  return {
  	diff: idx2 - idx1,
    remainders
  }
}

console.log(s(arr, val));