Array at index within the size of array is undefined

Question

I need to create an array initialized to the length of an object. Then be able to insert new data into an index within the array.

Code example:

$scope.holder = new Array($scope.x.length);
$scope.holder[0].new_data = response.data;

However the above will give error:

TypeError: Cannot set 'new_data' of undefined

How can this be if I specified the size of the array? Is the array not meant to have three objects in it. How can I solve this problem?

$scope.holder[0] is not defined yet, array has three undefined items — Hacketo
– Hacketo, Commented Nov 13, 2015 at 14:56

Oleksandr T. · Accepted Answer · 2015-11-13 14:55:52Z

3

In this case first [0] element in Array must be Object because now it is undefined and you can not assign property to undefined, you need create empty Object ({}) and then assign properties to it

$scope.holder = new Array($scope.x.length);
$scope.holder[0] = {};
$scope.holder[0].new_data = response.data;

answered Nov 13, 2015 at 14:55

Oleksandr T.

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Comments

z1m.in · Accepted Answer · 2015-11-13 15:17:44Z

3

$scope.holder = new Array($scope.x.length);
$scope.holder[0] = {'new_data':  response.data};

UPD: Or you can create array of objects

$scope.holder = Array.apply(null, Array($scope.x.length)).map(function () { return new Object(); })
$scope.holder[0].new_data = response.data;

edited Nov 13, 2015 at 15:17

answered Nov 13, 2015 at 14:55

z1m.in

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1 Comment

cfl Over a year ago

Works aswell thank you! ai jai jai such silly things

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