I need to implement a functionality very similar to IntelliSense in Visual Studio:
- code completion
- syntax checking
But in a web page.
Is there any framework out there to achieve so? What would be the best approach for it?
Well I've been using CodeMirror in a TinyMCE plugin that I've done a couple edits to; and I just now realized that you can enable code hinting as well as syntax highlighting which I knew. Currently hinting support is available for JS, XML, HTML, Python, SQL, CSS/LESS/SCSS and "any word". It should be quite easy to add hinting support for other languages given those example files and a good understanding of the other language.
CodeMirror is open-source under the MIT License and free. Optionally you can also purchase a commercial support license.