如何从JavaScript调用C＃函数？

Question

I want to call CsharpFunction , a C# function in code-behind, from JavaScript. I tried the code below but whether the JavaScript condition is True or False , CsharpFunction was called regardless!

JavaScript code:

if (Javascriptcondition > 0) {
   <%CsharpFunction();%>
}

C# code behind:

protected void CsharpFunction()
{
  // Notification.show();
}

How do I call a C# function from JavaScript?

Answer 1

You can use a Web Method and Ajax:

<script type="text/javascript">             //Default.aspx
   function DeleteKartItems() {     
         $.ajax({
         type: "POST",
         url: 'Default.aspx/DeleteItem',
         data: "",
         contentType: "application/json; charset=utf-8",
         dataType: "json",
         success: function (msg) {
             $("#divResult").html("success");
         },
         error: function (e) {
             $("#divResult").html("Something Wrong.");
         }
     });
   }
</script>

[WebMethod]                                 //Default.aspx.cs
public static void DeleteItem()
{
    //Your Logic
}

Answer 2

.CS File    
    namespace Csharp
    {
      public void CsharpFunction()
      {
        //Code;
      }
    }

    JS code:
    function JSFunction() {
            <%#ProjectName.Csharp.CsharpFunction()%> ;
    }

Note :in JS Function when call your CS page function.... first name of project then name of name space of CS page then function name

Answer 3

A modern approach is to use ASP.NET Web API 2 (server-side) with jQuery Ajax (client-side).

Like page methods and ASMX web methods, Web API allows you to write C# code in ASP.NET which can be called from a browser or from anywhere, really!

Here is an example Web API controller, which exposes API methods allowing clients to retrieve details about 1 or all products (in the real world, products would likely be loaded from a database):

public class ProductsController : ApiController
{
    Product[] products = new Product[] 
    { 
        new Product { Id = 1, Name = "Tomato Soup", Category = "Groceries", Price = 1 }, 
        new Product { Id = 2, Name = "Yo-yo", Category = "Toys", Price = 3.75M }, 
        new Product { Id = 3, Name = "Hammer", Category = "Hardware", Price = 16.99M } 
    };

    [Route("api/products")]
    [HttpGet]
    public IEnumerable<Product> GetAllProducts()
    {
        return products;
    }

    [Route("api/product/{id}")]
    [HttpGet]
    public IHttpActionResult GetProduct(int id)
    {
        var product = products.FirstOrDefault((p) => p.Id == id);
        if (product == null)
        {
            return NotFound();
        }
        return Ok(product);
    }
}

The controller uses this example model class:

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Category { get; set; }
    public decimal Price { get; set; }
}

Example jQuery Ajax call to get and iterate over a list of products:

$(document).ready(function () {
    // Send an AJAX request
    $.getJSON("/api/products")
        .done(function (data) {
            // On success, 'data' contains a list of products.
            $.each(data, function (key, item) {
                // Add a list item for the product.
                $('<li>', { text: formatItem(item) }).appendTo($('#products'));
            });
        });
});

Not only does this allow you to easily create a modern Web API, you can if you need to get really professional and document it too, using ASP.NET Web API Help Pages and/or Swashbuckle .

Web API can be retro-fitted (added) to an existing ASP.NET Web Forms project. In that case you will need to add routing instructions into the Application_Start method in the file Global.asax :

RouteTable.Routes.MapHttpRoute(
    name: "DefaultApi",
    routeTemplate: "api/{controller}/{id}",
    defaults: new { id = System.Web.Http.RouteParameter.Optional }
);

Documentation

• Tutorial: Getting Started with ASP.NET Web API 2 (C#)
• Tutorial for those with legacy sites: Using Web API with ASP.NET Web Forms
• MSDN: ASP.NET Web API 2

Answer 4

Server-side functions are on the server-side, client-side functions reside on the client. What you can do is you have to set hidden form variable and submit the form, then on page use Page_Load handler you can access value of variable and call the server method.

More info can be found here and here

Answer 5

如果要从客户端进行服务器调用，则应使用Ajax-查看类似Jquery的东西，并使用$ .Ajax（）或$ .getJson（）来调用服务器函数，具体取决于您返回的是哪种类型您要执行的动作或动作。

Answer 6

Use Blazor http://learn-blazor.com/architecture/interop/

Here's the C#:

namespace BlazorDemo.Client
{
   public static class MyCSharpFunctions
   {
       public static void CsharpFunction()
       {
          // Notification.show();
       }
   }
}

Then the Javascript:

const CsharpFunction = Blazor.platform.findMethod(
"BlazorDemo.Client",
"BlazorDemo.Client",
"MyCSharpFunctions",
"CsharpFunction"
);
if (Javascriptcondition > 0) {
   Blazor.platform.callMethod(CsharpFunction, null)
}

Answer 7

You can't. Javascript runs client side, C# runs server side.

In fact, your server will run all the C# code, generating Javascript. The Javascript then, is run in the browser. As said in the comments, the compiler doesn't know Javascript.

To call the functionality on your server, you'll have to use techniques such as AJAX, as said in the other answers.