Added initialization using a CSS string selector or an HTMLElement object

Author: ZsharE

README.md

@@ -15,9 +15,15 @@ A simple and easy JavaScript library for highlighting .NET stack traces
 [Stack Trace Formatter - Online pretty print of .NET stack traces](https://elmah.io/tools/stack-trace-formatter/)
 
 #### Initialization
+Using a string that represents a CSS selector:
 ```javascript
 const stack = new netStack('.stacktrace');
 ```
+Passing an HTMLElement object:
+```javascript
+const stackElement = document.querySelector('.stacktrace');
+const stack = new netStack(stackElement);
+```
 
 #### Default values for classes
 ```javascript

netstack.js

@@ -20,7 +20,13 @@
 
     function netStack(element, options) {
         if (typeof document !== 'undefined') {
-            this.element = document.querySelector(element);
+            if (typeof element === 'string') {
+                this.element = document.querySelector(element);
+            } else if (element instanceof HTMLElement) {
+                this.element = element;
+            } else {
+                throw new Error('The element parameter must be a selector string or an HTMLElement.');
+            }
         } else {
             throw new Error('netStack requires a DOM environment');
         }