Cannot acces object from javascript

Question

In my ASP.NET MVC application, in ..\Views\Shared_Layout.cshtml I have the following line of code:

> <script type="text/javascript" src="http://mycontrols.com/Scripts/MyConstants.js"></script>

File MyConstants.js contains below:

var MyConstants = function() {
   return {
       DataObject1: {
          MyEnum1: {
             Item0: 0,
             Item1: 1,
             Item3: 2
          }
       },
       DataObject2: {
          MyEnum2: {
             Item0: 0,
             Item1: 1,
             Item3: 2
          }
       }
   };
};

Now from my view (Index.cshtml) I am trying to access in javascript to an item from MyEnum1:

var myEnum = MyConstants.DataObject1.MyEnum1.Item1;

but it does not work, below the error en devtools in chrome:

jQuery.Deferred exception: Cannot read property 'MyEnum1'of undefined TypeError: Cannot read property 'MyEnum1' of undefined

jQuery.Deferred exception would occur when your code is inside a jquery callback (eg doc.ready) when the property doesn't exist. If you're using () (or not) correctly according to Rory's answer then it's possible your code is running before your var has been setup correct (eg your <script src=myconstants.js is not working. Add an alert as the first line in the include script to ensure it's working. — fdomn-m
– fdomn-m, Commented Feb 8, 2021 at 15:07

Rory McCrossan · Accepted Answer · 2021-02-08 14:38:14Z

2

MyConstants is a function which returns an object, so you need to invoke it:

var myEnum = MyConstants().DataObject1.MyEnum1.Item1;

If you'd prefer to keep your current syntax to retrieve the value, then you need to convert MyConstants to an object:

var MyConstants = {
  DataObject1: {
    MyEnum1: {
      Item0: 0,
      Item1: 1,
      Item3: 2
    }
  },
  DataObject2: {
    MyEnum2: {
      Item0: 0,
      Item1: 1,
      Item3: 2
    }
  }
};

edited Feb 8, 2021 at 14:38

answered Feb 8, 2021 at 14:23

Rory McCrossan

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3 Comments

Willy Over a year ago

I have changed to MyConstants() instead of using MyConstants but it does not work.From devtools in chrome I have checked this line and chrome gets MyConstants.DataObject1.MyEnum1.Item1 even if I type in javascript MyConstants().DataObject1.MyEnum1.Item1

Rory McCrossan Over a year ago

In which case we need more information about the error, and how and when you include the script in the page, as the example above works fine.

Willy Over a year ago

Finally I have solved, change was not being applied correctly. After clearing chrome cache and history it works. Thx.

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