maintain the selection of radio button after redirect

To maintain the state of a selected radio button after a page redirect, you can use localStorage or sessionStorage in JavaScript. Here’s a simple example of how you can do it:

// Run this when the radio button is clicked
$('input[type=radio][name=flag]').change(function() {
    // Save the selected radio button value in localStorage
    localStorage.setItem('selectedRadioButton', this.value);
});

// Run this when the page loads
$(document).ready(function() {
    // Get the selected radio button value from localStorage
    var selectedRadioButton = localStorage.getItem('selectedRadioButton');

    // If there was a selected radio button saved
    if (selectedRadioButton) {
        // Check the saved radio button
        $('input[type=radio][name=flag][value=' + selectedRadioButton + ']').prop('checked', true);
    }
});

This script will save the value of the selected radio button in the user’s browser when a radio button is clicked. Then, when the page is loaded, it will check if there is a saved radio button value and select that radio button.

Please replace 'flag' with the actual name attribute of your radio buttons. Also, make sure to include jQuery in your project for this script to work12.

Remember, localStorage persists across sessions and will work even if the user closes and reopens their browser, while sessionStorage is limited to the current session and will be cleared when the user closes their browser. Choose the one that best fits your needs.

Please note that this method will not work if the user has disabled web storage in their browser settings. In such cases, you might need to consider server-side solutions.

Yes you can do that with JS only also, but that won't be a good approach, here is an example

Note:- You can increase the expiration time from 7 days to any number of days

@Html.RadioButtonFor(model => model.flag, "R", new { @id = "oflag1" })
Refusal   

@Html.RadioButtonFor(model => model.flag, "RJ", new { @id = "oflag2" })
Return to JTP    

@Html.RadioButtonFor(model => model.flag, "RA", new { @id = "oflag4" })
Call for Addln.Particulars   

@Html.RadioButtonFor(model => model.flag, "FC", new { @id = "oflag3" })
Forward to Chairman

@Html.ValidationMessageFor(model => model.flag, "", new { @class = "text-danger" })

Can this solution can be resolve by js?

To maintain the value you have to do something like this

[HttpPost]
public ActionResult YourPostAction(YourModel model)
{
    // Save the selected flag value in TempData
    TempData["SelectedFlag"] = model.flag;

    // Perform other actions if needed

    // Redirect to another action or view
    return RedirectToAction("YourRedirectedAction");
}
public ActionResult YourRedirectedAction()
{
    // Retrieve the selected flag value from TempData
    var selectedFlag = TempData["SelectedFlag"]?.ToString();

    // Create a new model or retrieve an existing one
    YourModel model = new YourModel
    {
        flag = selectedFlag
    };

    return View(model);
}

@Html.RadioButtonFor(model => model.flag, "R", new { @id = "oflag1", @checked = (Model.flag == "R") })
Refusal   

@Html.RadioButtonFor(model => model.flag, "RJ", new { @id = "oflag2", @checked = (Model.flag == "RJ") })
Return to JTP    

@Html.RadioButtonFor(model => model.flag, "RA", new { @id = "oflag4", @checked = (Model.flag == "RA") })
Call for Addln.Particulars   

@Html.RadioButtonFor(model => model.flag, "FC", new { @id = "oflag3", @checked = (Model.flag == "FC") })
Forward to Chairman

@Html.ValidationMessageFor(model => model.flag, "", new { @class = "text-danger" })