html javascript - array remove (splice)

const arr0 = [0,1,2,3,4,5,6,7]
const arr1 = arr0.splice(1,3)
console.log(arr0) // [0,4,5,6,7]
console.log(arr1) // [1,2,3]

const arr2 = ['O', 'I', 'II', 'III', 'IV', 'V', 'VI']
arr2.splice(1, 0, 'a') // insert
console.log(arr2) // ['O', 'a', 'I', 'II', 'III', 'IV', 'V', 'VI']
arr2.splice(4, 1, 'b') // replace
console.log(arr2) // ['O', 'a', 'I', 'II', 'b', 'IV', 'V', 'VI']

const arr3 = [
  {
    name: 'arr I'
  },
  {
    name: 'arr II'
  },
  {
    name: 'arr III'
  }
]
const obj = arr3[1]

arr3.splice(arr3.indexOf(obj), 1)
console.log(arr3) // arr I, arr III