SOURCE

let arr = [1, 4, 6, 1, 2, 8]

// 去重 
Array.prototype.unRepeat = function () {
  let obj = {}, res = null
  // this.forEach( item => {
  //   obj[ item ] = true
  // })
  while( res = this.shift() ) {
    obj[ res ] = true
  }
  Object.keys( obj ).forEach( key => {
    this.push( key )
  })
  return this
}

arr = arr.unRepeat()
console.log( arr )