if you are using razor engine template then do the following
in your view write :
<script> var myJsVariable = '@ViewBag.MyVariable' </script>
UPDATE: A more appropriate approach is to define a set of configuration on the master layout for example, base url, facebook API Key, Amazon S3 base URL, etc ...```
<head>
<script>
var AppConfig = @Html.Raw(Json.Encode(new {
baseUrl: Url.Content("~"),
fbApi: "get it from db",
awsUrl: "get it from db"
}));
</script>
</head>
And you can use it in your JavaScript code as follow:
<script>
myProduct.fullUrl = AppConfig.awsUrl + myProduct.path;
alert(myProduct.fullUrl);
</script>