前端手动封装数组的foreach,map,filter,every,some,Reduce,reduceRight方法

我是歌谣 放弃很容易 但坚持一定很酷
公众号小歌谣 谢谢关注

前言

Foreach

Array.prototype.myForEach = function (cb) {
  var _arr = this;
  var _len = _arr.length;
  var _arg2 = arguments[1] || window;

  for (var i = 0; i < _len; i ++) {
    cb.apply(_arg2, [_arr[i], i, _arr]);
  }
}

Map

Array.prototype.myMap  = function (cb) {
  var _arr = this;
  var _len = _arr.length;
  var _arg2 = arguments[1] || window;
  var _newArr = [];
  var _item;
  var _res;

  for (var i = 0; i < _len; i ++) {
    _item = deepClone(_arr[i]);
    _res = cb.apply(_arg2, [_item, i, _arr]);
    _res && _newArr.push(_res);
  }

  return _newArr;
}

Filter

Array.prototype.myFilter = function (cb) {
  var _arr = this;
  var _len = _arr.length;
  var _arg2 = arguments[1] || window;
  var _newArr = [];
  var _item;

  for (var i = 0; i < _len; i ++) {
    _item = deepClone(_arr[i]);
    cb.apply(_arg2, [_item, i, _arr]) ? _newArr.push(_item) : '';
  }

  return _newArr;
}

Every

Array.prototype.myEvery = function (cb) {
  var _arr = this;
  var _len = _arr.length;
  var arg2 = arguments[1] || window;
  var _res = true;

  for (var i = 0; i < _len; i ++) {
    if (!cb.apply(arg2, [_arr[i], i, _arr])) {
      _res = false;
      break;
    }
  }

  return _res;
}

Some

Array.prototype.mySome = function (cb) {
  var _arr = this;
  var _len = _arr.length;
  var _arg2 = arguments[1] || window;
  var _res = false;

  for (var i = 0; i < _len; i ++) {
    if (cb.apply(_arg2, [_arr[i], i, _arr])) {
      _res = true;
      break;
    }
  }

  return _res;
}

Reduce

function deepClone (origin, target) {
  var tar = target || {};
  var toStr = Object.prototype.toString;
  var arrayType = '[object Array]';

  for (var k in origin) {
    if (origin.hasOwnProperty(k)) {
      if (typeof origin[k] === 'object' && origin[k] !== null) {
        tar[k] = toStr.call(origin[k]) === arrayType ? [] : {};
        deepClone(origin[k], tar[k]);
      } else {
        tar[k] = origin[k];
      }
    }
  }

  return tar;
}

Array.prototype.myReduce = function (cb, initialValue) {
  var _arr = this;
  var _len = _arr.length;
  var _arg3 = arguments[2] || window;
  var _item;

  for (var i = 0; i < _len; i ++) {
    _item = deepClone(_arr[i]);
    initialValue = cb.apply(_arg3, [initialValue, _item, i, _arr]);
  }

  return initialValue;
}

reduceRight

Array.prototype.myReduceRight = function (cb, initialValue) {
  var _arr = this;
  var _len = _arr.length;
  var _arg3 = arguments[2] || window;
  var _item;

  for (var i = _len; i >= 0; i --) {
    _item = deepClone(_arr[i]);
    initialValue = cb.apply(_arg3, [initialValue, _item, i, _arr]);
  }

  return initialValue;
}

我是歌谣放弃很难 但是坚持一定很酷