Making a JavaScript call to a WCF service hosted on a different domain involves several steps to handle cross-domain requests. This is because web browsers implement a security policy called the Same-Origin Policy, which prevents JavaScript code from making requests to resources on a different domain by default.

Here are the steps to make a JavaScript call to a WCF service hosted on a different domain:

1. Enable Cross-Origin Resource Sharing (CORS) on the WCF service. CORS is a mechanism that allows web servers to specify which origins are allowed to access its resources. You can enable CORS on the WCF service by adding the appropriate headers to the response.

2. Use the jQuery library to make the AJAX request. jQuery provides a simple and easy-to-use API for making AJAX requests, including support for cross-domain requests.

3. Set the “dataType” parameter to “jsonp”. JSONP (JSON with Padding) is a technique for making cross-domain requests by using a script tag to load the response from the remote server. jQuery handles the details of creating and executing the script tag.

4. Set the “jsonpCallback” parameter to a unique function name. This parameter specifies the name of the callback function that will be executed when the response is received. The function name should be unique to avoid conflicts with other functions on the page.

5. Use the “success” callback function to handle the response. The “success” function is called when the response is received and can be used to process the data returned by the WCF service.

Here is an example of making a JavaScript call to a WCF service hosted on a different domain using jQuery:

$.ajax({
  type: "GET",
  url: "https://wcf.example.com/MyService.svc/GetData",
  dataType: "jsonp",
  jsonpCallback: "myCallback",
  success: function(data) {
    // Handle the response data
    console.log(data);
  }
});

function myCallback(data) {
  // Handle the response data
  console.log(data);
}

In this example, the WCF service is hosted on the domain “wcf.example.com”, and the “GetData” operation returns JSON data. The “jsonpCallback” parameter is set to “myCallback”, and the “success” function logs the response data to the console.

Overall, making a JavaScript call to a WCF service hosted on a different domain requires enabling CORS on the WCF service and using the appropriate AJAX settings in the client-side JavaScript code. With the right configuration, you can easily access and consume data from remote WCF services in your web applications.