Using Razor within JavaScript

Question

Is it possible or is there a workaround to use Razor syntax within JavaScript that is in a view (cshtml)?

I am trying to add markers to a Google map... For example, I tried this, but I'm getting a ton of compilation errors:

<script type="text/javascript">

    // Some JavaScript code here to display map, etc.

    // Now add markers
    @foreach (var item in Model) {

        var markerlatLng = new google.maps.LatLng(@(Model.Latitude), @(Model.Longitude));
        var title = '@(Model.Title)';
        var description = '@(Model.Description)';
        var contentString = '<h3>' + title + '</h3>' + '<p>' + description + '</p>'

        var infowindow = new google.maps.InfoWindow({
            content: contentString
        });

        var marker = new google.maps.Marker({
            position: latLng,
            title: title,
            map: map,
            draggable: false
        });

        google.maps.event.addListener(marker, 'click', function () {
            infowindow.open(map, marker);
        });
    }
</script>

Answer 1

Use the <text> pseudo-element, as described here, to force the Razor compiler back into content mode:

<script type="text/javascript">

    // Some JavaScript code here to display map, etc.


    // Now add markers
    @foreach (var item in Model) {
        <text>
            var markerlatLng = new google.maps.LatLng(@(Model.Latitude), @(Model.Longitude));
            var title = '@(Model.Title)';
            var description = '@(Model.Description)';
            var contentString = '<h3>' + title + '</h3>' + '<p>' + description + '</p>'

            var infowindow = new google.maps.InfoWindow({
                content: contentString
            });

            var marker = new google.maps.Marker({
                position: latLng,
                title: title,
                map: map,
                draggable: false
            });

            google.maps.event.addListener(marker, 'click', function () {
                infowindow.open(map, marker);
            });
        </text>
    }
</script>

Update:

Scott Guthrie recently posted about @: syntax in Razor, which is slightly less clunky than the <text> tag if you just have one or two lines of JavaScript code to add. The following approach would probably be preferable, because it reduces the size of the generated HTML. (You could even move the addMarker function to a static, cached JavaScript file to further reduce the size):

<script type="text/javascript">

    // Some JavaScript code here to display map, etc.
    ...
    // Declare addMarker function
    function addMarker(latitude, longitude, title, description, map)
    {
        var latLng = new google.maps.LatLng(latitude, longitude);
        var contentString = '<h3>' + title + '</h3>' + '<p>' + description + '</p>';

        var infowindow = new google.maps.InfoWindow({
            content: contentString
        });

        var marker = new google.maps.Marker({
            position: latLng,
            title: title,
            map: map,
            draggable: false
        });

        google.maps.event.addListener(marker, 'click', function () {
            infowindow.open(map, marker);
        });
    }

    // Now add markers
    @foreach (var item in Model) {
        @:addMarker(@item.Latitude, @item.Longitude, '@item.Title', '@item.Description', map);
    }
</script>

Updated the above code to make the call to addMarker more correct.

To clarify, the @: forces Razor back into text mode, even though addMarker call looks a lot like C# code. Razor then picks up the @item.Property syntax to say that it should directly output the contents of those properties.

Update 2

It's worth noting that View code really isn't a good place to put JavaScript code. JavaScript code should be placed in a static .js file, and then it should get the data that it needs either from an Ajax call or by scanning data- attributes from the HTML. Besides making it possible to cache your JavaScript code, this also avoids issues with encoding, since Razor is designed to encode for HTML, but not JavaScript.

View Code

@foreach(var item in Model)
{
    <div data-marker="@Json.Encode(item)"></div>
}

JavaScript code

$('[data-marker]').each(function() {
    var markerData = $(this).data('marker');
    addMarker(markerData.Latitude, markerData.Longitude,
              markerData.Description, markerData.Title);
});

Answer 2

I just wrote this helper function. Put it in App_Code/JS.cshtml:

@using System.Web.Script.Serialization
@helper Encode(object obj)
{
    @(new HtmlString(new JavaScriptSerializer().Serialize(obj)));
}

Then in your example, you can do something like this:

var title = @JS.Encode(Model.Title);

Notice how I don't put quotes around it. If the title already contains quotes, it won't explode. Seems to handle dictionaries and anonymous objects nicely too!

Answer 3

You're trying to jam a square peg in a round hole.

Razor was intended as an HTML-generating template language. You may very well get it to generate JavaScript code, but it wasn't designed for that.

For instance: What if Model.Title contains an apostrophe? That would break your JavaScript code, and Razor won't escape it correctly by default.

It would probably be more appropriate to use a String generator in a helper function. There will likely be fewer unintended consequences of that approach.

Answer 4

What specific errors are you seeing?

Something like this could work better:

<script type="text/javascript">

//now add markers
 @foreach (var item in Model) {
    <text>
      var markerlatLng = new google.maps.LatLng(@Model.Latitude, @Model.Longitude);
      var title = '@(Model.Title)';
      var description = '@(Model.Description)';
      var contentString = '<h3>' + title + '</h3>' + '<p>' + description + '</p>'
    </text>
}
</script>

Note that you need the magical <text> tag after the foreach to indicate that Razor should switch into markup mode.

Answer 5

That will work fine, as long as it's in a CSHTML page and not an external JavaScript file.

The Razor template engine doesn't care what it's outputting and does not differentiate between <script> or other tags.

However, you need to encode your strings to prevent XSS attacks.

Answer 6

I prefer "<!--" "-->" like a "text>"

<script type="text/javascript">
//some javascript here     

@foreach (var item in itens)
{                 
<!--  
   var title = @(item.name)
    ...
-->

</script>

Answer 7

One thing to add - I found that Razor syntax hilighter (and probably the compiler) interpret the position of the opening bracket differently:

<script type="text/javascript">
    var somevar = new Array();

    @foreach (var item in items)
    {  // <----  placed on a separate line, NOT WORKING, HILIGHTS SYNTAX ERRORS
        <text>
        </text>
    }

    @foreach (var item in items) {  // <----  placed on the same line, WORKING !!!
        <text>
        </text>
    }
</script>

Answer 8

A simple and a good straight-forward example:

<script>
    // This gets the username from the Razor engine and puts it
    // in JavaScript to create a variable I can access from the
    // client side.
    //
    // It's an odd workaraound, but it works.
    @{
        var outScript = "var razorUserName = " + "\"" + @User.Identity.Name + "\"";
    }
    @MvcHtmlString.Create(outScript);
</script>

This creates a script in your page at the location you place the code above which looks like the following:

<script>
    // This gets the username from the Razor engine and puts it
    // in JavaScript to create a variable I can access from
    // client side.
    //
    // It's an odd workaraound, but it works.

    var razorUserName = "daylight";
</script>

Now you have a global JavaScript variable named razorUserName which you can access and use on the client. The Razor engine has obviously extracted the value from @User.Identity.Name (server-side variable) and put it in the code it writes to your script tag.

Answer 9

The following solution seems more accurate to me than combine JavaScript with Razor. Check this out: https://github.com/brooklynDev/NGon

You can add almost any complex data to ViewBag.Ngon and access it in JavaScript

In the controller:

public class HomeController : Controller
{
    public ActionResult Index()
    {
        var person = new Person { FirstName = "John", LastName = "Doe", Age = 30 };
        ViewBag.NGon.Person = person;
        return View();
    }
}

In JavaScript:

<script type="text/javascript">
    $(function () {
        $("#button").click(function () {
            var person = ngon.Person;
            var div = $("#output");
            div.html('');
            div.append("FirstName: " + person.FirstName);
            div.append(", LastName: " + person.LastName);
            div.append(", Age: " + person.Age);
        });
    });
</script>

It's allows any plain old CLR objects (POCOs) that can be serialized using the default JavascriptSerializer.

Answer 10

There is also one more option than @: and <text></text>.

Using <script> block itself.

When you need to do large chunks of JavaScript depending on Razor code, you can do it like this:

@if(Utils.FeatureEnabled("Feature")) {
    <script>
        // If this feature is enabled
    </script>
}

<script>
    // Other JavaScript code
</script>

Pros of this manner is that it doesn't mix JavaScript and Razor too much, because mixing them a lot will cause readability issues eventually. Also large text blocks are not very readable either.

Answer 11

None of the previous solutions work correctly... I have tried all the ways, but it did not give me the expected result... At last I found that there are some errors in the code... And the full code is given below.

<script type="text/javascript">

    var map = new google.maps.Map(document.getElementById('map'), {
        zoom: 10,
        center: new google.maps.LatLng(23.00, 90.00),
        mapTypeId: google.maps.MapTypeId.ROADMAP
    });

    @foreach (var item in Model)
    {
        <text>
            var markerlatLng = new google.maps.LatLng(@(item.LATITUDE), @(item.LONGITUDE));
            var title = '@(item.EMP_ID)';
            var description = '@(item.TIME)';
            var contentString = '<h3>' + "Employee " +title+ " was here at "+description+ '</h3>' + '<p>'+" "+ '</p>'

            var infowindow = new google.maps.InfoWindow({
                // content: contentString
            });

            var marker = new google.maps.Marker({
                position: markerlatLng,
                title: title,
                map: map,
                draggable: false,
                content: contentString
            });

            google.maps.event.addListener(marker, 'click', (function (marker) {
                return function () {
                    infowindow.setContent(marker.content);
                    infowindow.open(map, marker);
                }
            })(marker));
        </text>
    }
</script>

Answer 12

I finally found the solution (*.vbhtml):

function razorsyntax() {
    /* Double */
    @(MvcHtmlString.Create("var szam =" & mydoublevariable & ";"))
    alert(szam);

    /* String */
    var str = '@stringvariable';
    alert(str);
}

Answer 13

Those who, like me, don't have Json.Encode available can try this.

<script type="text/javascript">
    var model = @Html.Raw(Json.Serialize(Model))
</script>