ES5等价于ES6的lambda搜索

Question

我在数组上进行了es6搜索，由于cordova不允许我使用lambda，因此无法将其重写为es5…

$scope.Contact.title = $scope.doctitles[$scope.doctitles.findIndex(x => x.id == $localStorage.data.contacts[$localStorage.data.itemID].title.id)];

Answer 1

$scope.Contact.title = $scope.doctitles[$scope.doctitles.findIndex(function(x) {
    return x.id == $localStorage.data.contacts[$localStorage.data.itemID].title.id;
})];

您只需将lambda替换为一个函数。

编辑:因为findIndex也是ES6，你可以使用这个polyfill:

if (!Array.prototype.findIndex) {
  Array.prototype.findIndex = function(predicate) {
    if (this == null) {
      throw new TypeError('Array.prototype.findIndex called on null or undefined');
    }
    if (typeof predicate !== 'function') {
      throw new TypeError('predicate must be a function');
    }
    var list = Object(this);
    var length = list.length >>> 0;
    var thisArg = arguments[1];
    var value;
    for (var i = 0; i < length; i++) {
      value = list[i];
      if (predicate.call(thisArg, value, i, list)) {
        return i;
      }
    }
    return -1;
  };
}

摘自https://developer.mozilla.org/pl/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex