[英]How to initialize an array with two empty objects in Javascript
I am making an angular controller and need to initialize an array with two empty objects so that two lines will appear on the screen and I need to initialize a new object in the array when a + button is clicked. 我正在制作一个角度控制器,需要用两个空对象初始化一个数组,这样屏幕上就会出现两行,我需要在单击+按钮时初始化数组中的新对象。 I am unsure about how to go about doing this.
我不确定如何去做这件事。
This is my best attempt: 这是我最好的尝试:
var myApp = angular.module('myApp', []);
myApp.controller('myController', ['$scope', '$q', function($scope, $q) {
$scope.arr = [card('',''),card('','')];
$scope.addLine = function(index){
$scope.arr.push(card('',''));
}
$scope.removeLine = function(index){
$scope.arr.splice(index, 1);
}
}]);
function card(term, definition){
this.term = term;
this.definition = definition;
}
You need to use the keyword new
to make an instance of card
: 您需要使用关键字
new
来制作card
实例:
$scope.arr = [new card('',''), new card('','')];
// ^ ^ See new keyword
$scope.addLine = function(index){
$scope.arr.push(new card('',''));
// ^ See new keyword
}
Also you should consider always Capitalize your constructors (This way you can indicate that its an constructor: 此外,您应该考虑始终大写您的构造函数(这样您可以指示它的构造函数:
new Card('', '');
function Card(...) {...}
You can also boil the need of the new
keyword away by checking with instanceof
: 您还可以通过使用
instanceof
进行检查来满足new
关键字的需求:
// No need for new anymore:
var card = Card(1, 2, 3);
console.log(card instanceof Card); // true
function Card(a, b, c) {
if (!(this instanceof Card)) return new Card(a, b, c);
this.a = a;
this.b = b;
// ...
}
[new card('',''), new card('','')]
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