JavaScript calls three method instances in the background

2020-03-26 21:30:02
OfStack

Method 1: direct use < % = % > call

JS: at the front desk


<script type="text/javascript">  
       var methodStr = "<%=BehindMethod() %>";  
       alert(methodStr);  
       </script>

After method:


public static string BehindMethod()
        {
            return " This is a background method ";
        }

Method 2: call with ajax

Js: at the front desk


<script type="text/javascript" src="js/jquery-1.4.3.min.js"></script>
 <script type="text/javascript"> 
var params = '{ext:"p9hp"}';  //Parameter, notice that the parameter name is the same as the background method parameter name & PI;            
        $(function(){
           $("#btnOk").click(function(){
            $.ajax({
                type:"POST",  //Request way
                url:"AjaxDemo.aspx/GetImg",  //Request path: page/method name
                data: params,     // parameter 
                dataType:"text",  
                contentType:"application/json; charset=utf-8",
                beforeSend:function(XMLHttpRequest){  
                    $("#tips").text(" Start calling the back method to get the image path , Please wait for ");
                    $("#imgFood").attr("src","image/loading.gif");
                },
                success:function(msg){  // successful 
                    $("#imgFood").attr("src",eval("("+msg+")").d);  
                    $("#tips").text(" End of call method ");
                },
                error:function(obj, msg, e){   // abnormal 
                    alert("OH,NO");
                }               
            });
        });
        });
</script>

The HTML page:


<body>
    <form id="form1" runat="server">
    <div>
    <label id="tips"></label>
       <img id="imgFood" />
       <input value=" Click on me to show you a picture " type="button" width="35px" id="btnOk"  />

    </div>
    </form>
</body>

Background method:


[System.Web.Services.WebMethod]
        public static string GetImg(string ext)
        {
            System.Threading.Thread.Sleep(5000);//Delay by 5 seconds to get some effect
            StringComparer sc = StringComparer.OrdinalIgnoreCase;
            string[] extArr = new string[] { "php", "asp", "aspx", "txt", "bmp" };
            bool f = extArr.Any(s=>sc.Equals(s,ext));   //Determines whether the passed suffix name exists

            if (f)
            {
                return "image/54222860.jpg";
            }
            return "image/star1.jpg";
        }

Method 3: AjaxPro (also ajax)

Step 1: download the AjaxPro. DLL (or AjaxPro.2. DLL) and add a reference to the project

Step 2: modify the configuration file web. Config


<system.web>
<httpHandlers>
      <!-- registered ajaxPro.2-->
      <add verb="*" path="*.ashx" type="AjaxPro.AjaxHandlerFactory,AjaxPro.2"/>
    </httpHandlers>
  </system.web>

Step 3: run time registration of AjaxPro in the page Page_Load event. Such as:


        protected void Page_Load(object sender, EventArgs e)
        {
            AjaxPro.Utility.RegisterTypeForAjax(typeof(AjaxDemo));  // registered 
        }

Step 4: create the server method and annotate it with [AjaxPro.AjaxMethod]


        [AjaxPro.AjaxMethod]
        public string GetImgByAjaxPro()
        {
            return "image/54222860.jpg";
        }

Step 5: foreground JS call:


 function GetMethodByAjaxPro() {
            var a = JustTest.AjaxDemo.GetImgByAjaxPro();//JustTest is the current namespace, and AjaxDemo is the background class
            document.getElementById("imgAjaxPro").src = a.value;
        }