Asked  7 Months ago    Answers:  5   Viewed   35 times

I'm writing a web page in ASP.NET. I have some JavaScript code, and I have a submit button with a click event.

Is it possible to call a method I created in ASP with JavaScript's click event?



Well, if you don't want to do it using Ajax or any other way and just want a normal ASP.NET postback to happen, here is how you do it (without using any other libraries):

It is a little tricky though... :)

i. In your code file (assuming you are using C# and .NET 2.0 or later) add the following Interface to your Page class to make it look like

public partial class Default : System.Web.UI.Page, IPostBackEventHandler{}

ii. This should add (using Tab-Tab) this function to your code file:

public void RaisePostBackEvent(string eventArgument) { }

iii. In your onclick event in JavaScript, write the following code:

var pageId = '<%=  Page.ClientID %>';
__doPostBack(pageId, argumentString);

This will call the 'RaisePostBackEvent' method in your code file with the 'eventArgument' as the 'argumentString' you passed from the JavaScript. Now, you can call any other event you like.

P.S: That is 'underscore-underscore-doPostBack' ... And, there should be no space in that sequence... Somehow the WMD does not allow me to write to underscores followed by a character!

Tuesday, June 1, 2021
answered 7 Months ago

You can't.


    function my_fun(){
           /.. some operations ../

That is a closure. my_fun() is defined only inside of that anonymous function. You can only call my_fun() if you declare it at the correct level of scope, i.e., globally.

$(function () {/* something */}) is an IIFE, meaning it executes immediately when the DOM is ready. By declaring my_fun() inside of that anonymous function, you prevent the rest of the script from "seeing" it.

Of course, if you want to run this function when the DOM has fully loaded, you should do the following:

function my_fun(){
    /* some operations */

    my_fun(); //run my_fun() ondomready

// just js
function js_fun(){
   my_fun(); //== call my_fun() again
Wednesday, July 28, 2021
answered 5 Months ago

Ok, I think this problem ended up being quite a bit simpler than I was making it (aren't they always). After performing a RTFM operation on the pbkdf2 spec, I ran some side-by-side tests with Node crypto and .NET crypto, and have made pretty good progress on a solution.

The following JavaScript code correctly parses the stored salt and subkey, then verifies the given password by hashing it with the stored salt. There are doubtless better / cleaner / more secure tweaks, so comments welcome.

// NodeJS implementation of crypto, I'm sure google's 
// cryptoJS would work equally well.
var crypto = require('crypto');

// The value stored in [dbo].[AspNetUsers].[PasswordHash]
var hashedPwd = "ADOEtXqGCnWCuuc5UOAVIvMVJWjANOA/LoVy0E4XCyUHIfJ7dfSY0Id+uJ20DTtG+A==";
var hashedPasswordBytes = new Buffer(hashedPwd, 'base64');

var hexChar = ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F"];

var saltString = "";
var storedSubKeyString = "";

// build strings of octets for the salt and the stored key
for (var i = 1; i < hashedPasswordBytes.length; i++) {
    if (i > 0 && i <= 16) {
        saltString += hexChar[(hashedPasswordBytes[i] >> 4) & 0x0f] + hexChar[hashedPasswordBytes[i] & 0x0f]
    if (i > 0 && i > 16) {
        storedSubKeyString += hexChar[(hashedPasswordBytes[i] >> 4) & 0x0f] + hexChar[hashedPasswordBytes[i] & 0x0f];

// password provided by the user
var password = 'welcome1';

// TODO remove debug - logging passwords in prod is considered 
// tasteless for some odd reason
console.log('cleartext: ' + password);
console.log('saltString: ' + saltString);
console.log('storedSubKeyString: ' + storedSubKeyString);

// This is where the magic happens. 
// If you are doing your own hashing, you can (and maybe should)
// perform more iterations of applying the salt and perhaps
// use a stronger hash than sha1, but if you want it to work
// with the [as of 2015] Microsoft Identity framework, keep
// these settings.
var nodeCrypto = crypto.pbkdf2Sync(new Buffer(password), new Buffer(saltString, 'hex'), 1000, 256, 'sha1');

// get a hex string of the derived bytes
var derivedKeyOctets = nodeCrypto.toString('hex').toUpperCase();

console.log("hex of derived key octets: " + derivedKeyOctets);

// The first 64 bytes of the derived key should
// match the stored sub key
if (derivedKeyOctets.indexOf(storedSubKeyString) === 0) {"passwords match!");
} else {
    console.warn("passwords DO NOT match!");
Thursday, August 12, 2021
answered 4 Months ago

This is definitely a CORS related issue. Luckily, it's easy to configure CORS for Function Apps in the portal. Just navigate to your Function App and then select Platform Features:

enter image description here

Select the CORS option under API which will take you to a screen where you can add the hostname of your clientside application:

enter image description here

Monday, August 23, 2021
Benoit Wickramarachi
answered 4 Months ago

You can do this by making sure that Btn_AddNewSite is a LinkButton.

<asp:LinkButton ID="Btn_AddNewSite" runat="server" OnClick="Btn_AddNewSite_Click"></asp:LinkButton>

Then you can use the javascript code that handles the LinkButton click in the Cell by using it's UniqueID.

e.Row.Cells[column].Attributes.Add("onclick", "__doPostBack('" + Btn_AddNewSite.UniqueID + "', '')");
Friday, November 19, 2021
answered 2 Weeks ago
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