How to initialize an array with two empty objects in Javascript

Question

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. I am unsure about how to go about doing this.

This is my best attempt:

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; } 

Answer 1

You need to use the keyword new to make an instance of card:

$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:

new Card('', ''); function Card(...) {...} 

You can also boil the need of the new keyword away by checking with instanceof:

// 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; // ... } 

Answer 2

[new card('',''), new card('','')] 

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