原生JS面试-手写题

使用promise实现sleep

function sleep(time) {
  return new Promise(resolve => setTimeout(resolve, time))
}

sleep(3000).then(() => {
  console.log('JavaScript')
})

实现数组chunk功能

Array.prototype.chunk = function(num) {
  const rv = []
  let temp = []
  for (let i = 0; i < this.length; i++) {
    const element = this[i]
    temp.push(element)
    if ((i + 1) % num === 0 || i === this.length - 1) {
      rv.push(temp)
      temp = []
    }
  }
  return rv
}

const arr = [1, 2, 3, 4, 5, 123, 21321]
const res = arr.chunk(3)
console.log(res)

快速排序

function quickSort(arr) {
  if (arr.length <= 1) {
    return arr
  }
  const pivotIndex = Math.floor(arr.length / 2)
  const pivotValue = arr.splice(pivotIndex, 1)[0]
  const left = []
  const right = []
  for (const item of arr) {
    if (item < pivotValue) {
      left.push(item)
    } else {
      right.push(item)
    }
  }
  return quickSort(left).concat([pivotValue], quickSort(right))
}

const res = quickSort([10, 123, 132, 213, -1])
console.log(res)