HIde JS file in a layout page using ASP.NET Core MVC

Better is to store the key in configuration file and read from there
"Crypto": {  
    "key": "abcd"  ,  
    "Iv":"agaha"  
  }  
 
In _Layout.cshtml

@using Microsoft.Extensions.Configuration  
 @inject IConfiguration Configuration   
   

Also disabled few keys as shown

document.addEventListener('keydown', function() {  
  if (event.keyCode == 123) {  
    alert("This function has been disabled to prevent you from stealing my code!");  
    return false;  
  } else if (event.ctrlKey && event.shiftKey && event.keyCode == 73) {  
    alert("This function has been disabled to prevent you from stealing my code!");  
    return false;  
  } else if (event.ctrlKey && event.keyCode == 85) {  
    alert("This function has been disabled to prevent you from stealing my code!");  
    return false;  
  }  
}, false);  
  
if (document.addEventListener) {  
  document.addEventListener('contextmenu', function(e) {  
    alert("This function has been disabled to prevent you from stealing my code!");  
    e.preventDefault();  
  }, false);  
} else {  
  document.attachEvent('oncontextmenu', function() {  
    alert("This function has been disabled to prevent you from stealing my code!");  
    window.event.returnValue = false;  
  });  
}  

There is no way to hide the JS code. JS-Scripts are running inside your Browser. So the Browser must know the JS-Scripts. And if the Browser know it, the user can have a look at them.

But all you can do is disable the the right click of mouse button using below code:

function disableclick(event){  
           if(event.button==2){ // this value is 3 for some othe browser  
            // Rest of code  
         return false;      
       }  
    }

Also not that you need to disable F12 key since pressing F12 open the developers console, which is actually bypass right click event