Evaluate Razor variable in javascript

Question

I need to evaluate a razor variable inside a JavaScript function. Given the following code:

 @{var unseenNotificationsExist = false;}
 
 @foreach(var notification in viewModel)
 {
    if (notification.WasSeen == false)
    {
      unseenNotificationsExist = true;
      break;
    }
 }

I need to evaluate the unseenNotificationsExist variable in JavaScript like this:

 if(@unseenNotificationsExist == true)
        $('#unseenNotifCount').addClass('notifNotSeen');

However, when I debug the JavaScript code, I get this:

if(True == true)

and also I get the following error:

Uncaught ReferenceError True is not defined

letmejustfixthat · Accepted Answer · 2021-06-18 08:55:44Z

5

var unseenNotificationsExist = @(unseenNotificationsExist?"true":"false") ;
//the line above must be part of your view

if(unseenNotificationsExist === true)
        $('#unseenNotifCount').addClass('notifNotSeen');
//this can be part of your js file or alternatively and less 
//preferably part of your view

edited Jun 18, 2021 at 8:55

letmejustfixthat

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answered Aug 8, 2013 at 8:44

Parv Sharma

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1 Comment

Octavian Epure Over a year ago

It also works including all the code in the javascript snippet in the view

Octavian Epure · Accepted Answer · 2013-08-08 08:50:44Z

4

I found a workaround: I added this

var True = true

Now, in javascript there is a variable "True" defined and the evaluation comes down to True == true, which returns true.

answered Aug 8, 2013 at 8:50

Octavian Epure

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Comments

Sajjad Ali Khan · Accepted Answer · 2017-01-18 02:36:35Z

2

I prefer to use Json.Encode , whenever i want to convert the model data to JSON objects or JSON variables .

For converting an object(dto) of model to javascript

var accountDto = @Html.Raw(Json.Encode(@Model.AccountDto))

For converting a (bool)property of model

var isTrue = @Json.Encode(Model.IsTrue)

answered Jan 18, 2017 at 2:36

Sajjad Ali Khan

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Comments

UweB · Accepted Answer · 2013-08-08 08:45:15Z

0

If you want to not have the the JavaScript rendered, use Daniele's suggestion.

If you insist on making the comparison in JavaScript:

if(@unseenNotificationsExist.ToString().ToLower() === true)

answered Aug 8, 2013 at 8:45

UweB

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5 Comments

Parv Sharma Over a year ago

Though this might work but it will be a good practice to change the varible into javascript our self and then manipulate it. Just depending upon ToString() wont be a good option

Parv Sharma Over a year ago

also this type of patten wont allow the user to separate all the js code in a separate file

UweB Over a year ago

It's not a pretty solution, agreed! But your solution will not allow a separate JS file either... ;-) EDIT: In fact, I take that back - you were certainly only referring to the if part.

Parv Sharma Over a year ago

why not.. i just making a global variable.. and i have edited my ans please check again

UweB Over a year ago

Yeah I see that now, it wasn't there when I posted, but I figured that out eventually.

Daniele · Accepted Answer · 2013-08-08 08:48:15Z

-1

You tried with:

if('@unseenNotificationsExist' === 'True')
        $('#unseenNotifCount').addClass('notifNotSeen');

edited Aug 8, 2013 at 8:48

answered Aug 8, 2013 at 8:42

Daniele

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4 Comments

Parv Sharma Over a year ago

it still will remain True and not true

Octavian Epure Over a year ago

Yes, I did, same result.

UweB Over a year ago

It's only missing an @ in front of the if imo, possibly curly braces too to make it a C#-if.

Daniele Over a year ago

the if is in javascript not razor

Alex Marculescu · Accepted Answer · 2013-08-08 08:49:53Z

-1

try using

if('@unseenNotificationsExist')

edited Aug 8, 2013 at 8:49

answered Aug 8, 2013 at 8:42

Alex Marculescu

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3 Comments

Alex Marculescu Over a year ago

My answer was incomplete, I edited it. This seems to work for me.

Parv Sharma Over a year ago

this will always go into true block because in js dosent matter you check if("True") or if("False")

Alex Marculescu Over a year ago

correct. you could not initialize the variable with false though, just declare it.

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