Calling JavaScript Function From CodeBehind

问题:

Can someone provide good examples of calling a JavaScript function From CodeBehind and Vice-versa?

回答1:

You may try this :

Page.ClientScript.RegisterStartupScript(this.GetType(),\"CallMyFunction\",\"MyFunction()\",true);

回答2:

C# to JavaScript: you can register script block to run on page like following:

ClientScript.RegisterStartupScript(GetType(),\"hwa\",\"alert(\'Hello World\');\",true);

replace alert() part with your function name.

For calling C# method from JavaScript you can use ScriptManager or jQuery. I personally use jQuery. You need to decorate the method that you want to call from JavaScript with WebMethod attribute. For more information regarding calling C# method (called PageMethod) from jQuery you can refer to Dave Ward\'s post.

回答3:

Calling a JavaScript function from code behind

Step 1 Add your Javascript code

<script type=\"text/javascript\" language=\"javascript\">
    function Func() {
        alert(\"hello!\")
    }
</script>

Step 2 Add 1 Script Manager in your webForm and Add 1 button too

Step 3 Add this code in your button click event

ScriptManager.RegisterStartupScript(this.Page, Page.GetType(), \"text\", \"Func()\", true);

回答4:

If you need to send a value as a parameter.

string jsFunc = \"myFunc(\" + MyBackValue + \")\";
ScriptManager.RegisterStartupScript(this.Page, Page.GetType(), \"myJsFn\", jsFunc, true);

回答5:

You cannot do this directly. Javascript is interpreted by browser and C# by server. What you can do to call a method from server using javscript is

• use webmethod as attribute in target methods.
• add scriptmanager setting EnablePageMethods as true
• add javascript code to call the methods through object PageMethods

Like this: step 1

 public partial class Products : System.Web.UI.Page 
   { 
     [System.Web.Services.WebMethod()] 
     [System.Web.Script.Services.ScriptMethod()] 
     public static List<Product> GetProducts(int cateogryID) 
     {
       // Put your logic here to get the Product list 
     }

step 2: adding scriptmanager on the page

 <asp:ScriptManager ID=\"ScriptManager1\" runat=\"server\" EnablePageMethods=\"true\" />

step 3: calling the method using javascript

function GetProductsByCategoryID(categoryID)
{
    PageMethods.GetProducts(categoryID, OnGetProductsComplete);
}

Take a look at this link.

To call a javascript function from server you can use a RegisterStartipScript:

ClientScript.RegisterStartupScript(GetType(),\"id\",\"callMyJSFunction()\",true);

回答6:

You cannot. Codebehind is running on the server while JavaScript is running on the client.

However, you can add <script type=\"text/javascript\">someFunction();</script> to your output and thus cause the JS function to be called when the browser is parsing your markup.

回答7:

Another thing you could do is to create a session variable that gets set in the code behind and then check the state of that variable and then run your javascript. The good thing is this will allow you to run your script right where you want to instead of having to figure out if you want it to run in the DOM or globally.

Something like this: Code behind:

Session[\"newuser\"] = \"false\" 

In javascript

var newuser = \'<%=Session[\"newuser\"]%>\';
 if (newuser == \"yes\")
     startTutorial();  

回答8:

IIRC Code Behind is compiled serverside and javascript is interpreted client side. This means there is no direct link between the two.

What you can do on the other hand is have the client and server communicate through a nifty tool called AJAX. http://en.wikipedia.org/wiki/Asynchronous_JavaScript_and_XML

回答9:

You can use literal:

this.Controls.Add(new LiteralControl(\"<script type=\'text/javascript\'>myFunction();</script>\"));

回答10:

ScriptManager.RegisterStartupScript(this, this.Page.GetType(),\"updatePanel1Script\", \"javascript:ConfirmExecute()\",true/>

回答11:

Working Example :_

<%@ Page Title=\"\" Language=\"C#\" MasterPageFile=\"~/MasterPage2.Master\" AutoEventWireup=\"true\" CodeBehind=\"History.aspx.cs\" Inherits=\"NAMESPACE_Web.History1\" %>

<asp:Content ID=\"Content1\" ContentPlaceHolderID=\"head\" runat=\"Server\">
    <%@ Register Assembly=\"AjaxControlToolkit\" Namespace=\"AjaxControlToolkit\" TagPrefix=\"ajax\" %>


 <script type=\"text/javascript\" src=\"https://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js\"></script> 

        <script type=\"text/javascript\">

            function helloFromCodeBehind() {
                alert(\"hello!\")
            }


        </script>

</asp:Content>

<asp:Content ID=\"Content2\" ContentPlaceHolderID=\"ContentPlaceHolder1\" runat=\"Server\">

 <div id=\"container\"  ></div>

</asp:Content>

Code Behind

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace NAMESPACE_Web
{
    public partial class History1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

            ScriptManager.RegisterStartupScript(this, GetType(), \"displayalertmessage\", \"helloFromCodeBehind()\", true);
        }

    }
}

Possible pitfalls:-

1. Code and HTML might not be in same namespace
2. CodeBehind=\"History.aspx.cs\" is pointing to wrong page
3. JS function is having some error

回答12:

I\'ve been noticing a lot of the answers here are using ScriptManager.RegisterStartupScript and if you are going to do that, that isn\'t the right way to do it. The right way is to use ScriptManager.RegisterScriptBlock([my list of args here]). The reason being is you should only be using RegisterStartupScript when your page loads (hence the name RegisterStartupScript).

In VB.NET:

ScriptManager.RegisterClientScriptBlock(Page, GetType(String), \"myScriptName\" + key, $\"myFunctionName({someJavascriptObject})\", True)

in C#:

ScriptManager.RegisterClientScriptBlock(Page, typeof(string), \"myScriptName\" + key, $\"myFunctionName({someJavascriptObject})\", true);

Of course, I hope it goes without saying that you need to replace key with your key identifier and should probably move all of this into a sub/function/method and pass in key and someJavascriptObject (if your javascript method requires that your arg is a javascript object).

MSDN docs:

https://msdn.microsoft.com/en-us/library/bb338357(v=vs.110).aspx

回答13:

You can expose C# methods on codebehind pages to be callable via JavaScript by using the ScriptMethod attribute.

You cannot call JavaScript from a CodeBehind - that code exists solely on the client.

回答14:

This is how I\'ve done it.

HTML markup showing a label and button control is as follows.

<body> 
  <form id=\"form1\" runat=\"server\"> 
  <div> 
    <asp:Label ID=\"lblJavaScript\" runat=\"server\" Text=\"\"></asp:Label> 
    <asp:Button ID=\"btnShowDialogue\" runat=\"server\" Text=\"Show Dialogue\" /> 
  </div> 
  </form> 
</body>

JavaScript function is here.

<head runat=\"server\"> 
  <title>Calling javascript function from code behind example</title> 
  <script type=\"text/javascript\"> 
    function showDialogue() { 
      alert(\"this dialogue has been invoked through codebehind.\"); 
    } 
  </script> 
</head>

Code behind to trigger the JavaScript function is here.

lblJavaScript.Text = \"<script type=\'text/javascript\'>showDialogue();</script>\";

回答15:

this works for me

object Json_Object=maintainerService.Convert_To_JSON(Jobitem);
ScriptManager.RegisterClientScriptBlock(this,GetType(), \"Javascript\", \"SelectedJobsMaintainer(\"+Json_Object+\"); \",true);

回答16:

You can\'t call a Javascript function from the CodeBehind, because the CodeBehind file contains the code that executes server side on the web server. Javascript code executes in the web browser on the client side.

回答17:

I used ScriptManager in Code Behind and it worked fine.

ScriptManager.RegisterStartupScript(UpdatePanel1, UpdatePanel1.GetType(), \"CallMyFunction\", \"confirm()\", true);

If you are using UpdatePanel in ASP Frontend. Then, enter UpdatePanel name and \'function name\' defined with script tags.

回答18:

ScriptManager.RegisterStartupScript(Page, GetType(), \"JavaFunction\", \"AlertError();\", true);

using your function is enough

回答19:

Try This in Code Behind and it will worked 100%

string script = \"window.onload = function() { YourJavaScriptFunctionName(); };\";
ClientScript.RegisterStartupScript(this.GetType(), \"YourJavaScriptFunctionName\", script, true);