JSFiddle - React, Tailwind, and code Playground

JavaScript

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

function s(arr, val) {
  let vals = [];
  let remainders = [];

  arr.forEach((item, index) => {
    val === item ? vals = vals.concat({item, index}) : remainders = remainders.concat(item)
  });
  
  return {
  	diff: vals[vals.length - 1].index - vals[0].index, 
    remainders
  }
}

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