Is there any good and logical ways to highlight code inside textarea via jQuery? If there is, please share.
You could use CodeMirror http://codemirror.net/
...a versatile text editor implemented in JavaScript for the browser. It is specialized for editing code, and comes with a number of language modes and addons that implement more advanced editing functionality.
A rich programming API and a CSS theming system are available for customizing CodeMirror to fit your application, and extending it with new functionality...