Find the unique number

Description

There is an array with some numbers. All numbers are equal except for one. Try to find it!
findUniq([ 1, 1, 1, 2, 1, 1 ]) === 2
findUniq([ 0, 0, 0.55, 0, 0 ]) === 0.55

My answer

function findUniq(arr) {
  const arr1 = arr.filter(ele => ele === arr[0]);
  const arr2 = arr.filter(ele => ele !== arr[0]);
  
  return (arr1.length > arr2.length) ? arr2[0] : arr1[0];
}

Other solutions

function findUniq(arr) {
  arr.sort((a,b)=>a-b);
  return arr[0]==arr[1]?arr.pop():arr[0]
}

function findUniq(arr) {
  return arr.find(n => arr.indexOf(n) === arr.lastIndexOf(n));
}