javascript 处理数组[each，map，reduce]

Posted 2021-05-04

var each = function (arr, callback) {
  for (var i = 0; i < arr.length; i++) {
    if (callback(arr[i], i) === false) break
  }
}

var map = function (arr, callback) {
  var res = []
  for (var i = 0; i < arr.length; i++) {
    res.push(callback(arr[i], i))
  }
  return res
}

var reduce = function (arr, callback, init) {
  var res = init
  for (var i = 0; i < arr.length; i++) {
    res = callback(res, arr[i], i)
  }
  return res
}