Asp.net dynamically loads user defined controls and converts them to HTML code

If the page is simply created using js, it takes a lot of code and is not intuitive.
In asp.net, we can actually create a user-defined control and return the user-defined control HTML code via an Ajax request.

public static string RangerUsControl(string controlName) 
{ 
StringBuilder build = new StringBuilder(); 
HtmlTextWriter htmlWriter = new HtmlTextWriter(new StringWriter(build)); 
UserControl uc = new UserControl(); 
Control ctrl=uc.LoadControl(controlName+".ascx");// Loads the user-defined control  TextBox txtBox1 = ctrl.FindControl("TextBox1") as TextBox;// To obtain id As a" TextBox1 "Control  
txtBox1.Text = " test "; // Initialize the control  string result; 
try 
{ 
ctrl.RenderControl(htmlWriter); 
} 
catch { } 
finally 
{ 
htmlWriter.Flush(); 
result=build.ToString(); 
} 
return result;// Return control HTML code  
} 
htmlWriter.Flush();