Hi SwanVW,

Thanks for your post.

SwanVW

I am learning how to use Ajax to call a server method and return some value. But, my test code can't return a sting.

Please refer to the following sample to call a web method using jQuery AJAX.

$("#btncallwebmethod").click(function () {
    $.ajax({
        type: "Post",

        url: "AjaxCallWebmethod.aspx/ReturnString",
        data: "{'firstName':'Swan','lastName':'W'}",

        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (data) {
            var mes = data.d;
            alert(mes);
        },
        error: function (err) {
            alert(err);
        }
    });
}) 

[WebMethod]
public static string ReturnString(string firstName, string lastName)
{
    string Text = "Hello" + firstName + lastName;
    return Text;
} 

For more information about jQuery AJAX, please refer to this link.

http://api.jquery.com/jquery.ajax/

Best Regards,

Fei Han