const splice = require('splice-array')
const array = [1, 2, 3]

splice(array, (x, i) => i % 2 === 1)  // returns [2]
console.log(array)                    // [2]

const array2 = [1, 2, 3]
splice.p(array2, (x, i) => {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve(i % 2 === 1)
    }, 100)
  })
})
.then(result => {
  console.log(result === array2)    // true
  console.log(result)               // [2]
})