Javascript Array filterBy(key, val, returnFirst)

// 05/12/16//from ww w.j  ava2s  .co m
Array.prototype.filterBy = function (key, val, returnFirst) {
    if (typeof key=='object') {
      returnFirst = val
    }
    var item = this.filter(function (x) {
      if (typeof key=='object') {
        var check = true
        Object.keys(key).forEach(function (k) {
          check = check && (x[k] == key[k])
        })
        return check
      }
      else {
        return x? (x[key] == val) : false
      }
    })

    return returnFirst? item[0] : item
};

'use strict';// w  w  w.  j  a v  a2  s . c om

var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; };

// 05/12/16
Array.prototype.filterBy = function (key, val, returnFirst) {
  if ((typeof key === 'undefined' ? 'undefined' : _typeof(key)) == 'object') {
    returnFirst = val;
  }
  var item = this.filter(function (x) {
    if ((typeof key === 'undefined' ? 'undefined' : _typeof(key)) == 'object') {
      var check = true;
      Object.keys(key).forEach(function (k) {
        check = check && x[k] == key[k];
      });
      return check;
    } else {
      return x ? x[key] == val : false;
    }
  });

  return returnFirst ? item[0] : item;
};