How do we use AddJavaScriptInterface of WebView in any game for iOS & Android to call a function at the Unity end from the web page end?

There is a WebPage hosted in a server. This page contains several buttons in it. I am opening this webpage within Unity in Android & iOS using UniWebView plugin. When this webpage is opened within UniWebView's webview, several buttons are displayed within the page. I want, when a user clicks a button in the web page, a function will get executed at the game end at the mobile end.

Moreover, I have seen a project in XCode, where UIWebView is being used. While loading the page in the webview, an object of a class is being sent with a key named "Native". The name of the class is JSInterface, which implements a JSExport type of interface. This JSInterface class implements all the functions of the JSExport interface class. When the user clicks a particular button within the web page, one of the functions in the JSInterface class gets called. This way a function at the native iOS end gets fired from within the web page.

Can anyone suggest me, how we can do the same in Unity?

 import UIKit
 
 class ViewController: UIViewController {
 
     @IBOutlet weak var baseWebView: UIWebView!
     override func viewDidLoad() {
         super.viewDidLoad()
         // Do any additional setup after loading the view, typically from a nib.
         let loadRequest = "https://staging.officialgeorgestraitcasino.com/event_handler/index.html"//TEST_URL//
         let request =  URLRequest(url: URL(string: loadRequest)!) as URLRequest
         baseWebView.loadRequest(request)
         
         let jsInterface = JSInterface()
         baseWebView.addJavascriptInterface(object: jsInterface, forKey: "Native")
     }
 
     override func didReceiveMemoryWarning() {
         super.didReceiveMemoryWarning()
         // Dispose of any resources that can be recreated.
     }
 
 
 }
 
 
 
 import Foundation
 import JavaScriptCore
 import UIKit
 
 @objc protocol MyExport : JSExport
 {
 //    --------- Testing index.html -----------
     func check(_ message : String)
     func sayGreeting(_ message: String, _ name: String)
     func sayGreeting()
     func anotherSayGreeting(_ message: String, name: String)
     func showDialog(_ title: String, _ message : String)
 //    ----------------------------------------
 //    func onLogin_voucher_ButtonClick(_ pageName: String)
     func onLogin_voucher_ButtonClick(_ pageName: String,_ back: String)
     func onClassicWebsiteClick()
     func onLogoutSuccess()
     func onSessionInvalid()
 }
 
 class JSInterface : NSObject, MyExport
 {
     var loginOrVoucherClicked: ((_ page: String, _ successOrBack: String) ->())?
     var classicWebsiteClicked: (() ->())?
     var logoutSuccess: (() ->())?
     var sessionInvalid: (() ->())?
     
 //    --------- Testing index.html -----------
     func check(_ message: String) {
         debugLog("JS Interface works!")
     }
     
     func sayGreeting(_ message: String, _ name: String)
     {
         debugLog("sayGreeting: \(message): \(name)")
     }
     
     func sayGreeting()
     {
         debugLog("sayGreeting")
     }
     
     func anotherSayGreeting(_ message: String, name: String)
     {
         debugLog("anotherSayGreeting: \(message): \(name)")
     }
 
     func showDialog(_ title: String, _ message : String)
     {
         DispatchQueue.main.async {
             UIAlertView(title: title, message: message, delegate: nil, cancelButtonTitle: "OK").show()
         }
     }
 //    ----------------------------------------
     
 //    func onLogin_voucher_ButtonClick(_ pageName: String){
 //        if loginOrVoucherClicked != nil {
 //            loginOrVoucherClicked!(pageName)
 //        }
 //    }
     
     func onLogin_voucher_ButtonClick(_ pageName: String,_ back: String) {
         debugLog("\(pageName)::::\(back)")
         if loginOrVoucherClicked != nil {
             loginOrVoucherClicked!(pageName, back)
         }
     }
     
     func onClassicWebsiteClick(){
         if classicWebsiteClicked != nil {
             classicWebsiteClicked!()
         }
     }
     
     func onLogoutSuccess(){
         if logoutSuccess != nil {
             logoutSuccess!()
         }
     }
     
     func onSessionInvalid() {
         if sessionInvalid != nil {
             sessionInvalid!()
         }
     }
 }