Thanks for your warning about the security issue.
Yeah, I am aware that there are a lot of conversion program out there already. But my reason being that this web application is going to be multi-purpose and multi-function for daily life task. So by adding this to the web application is just for being more complete. Just like there are many candy stores available, among them definitely they do sell the same candy, but people will prefer to go to other candy store in the future if they find your candy store is not complete enough.
Okay, I have just started to use the p tag, just that would require more effort than pre tag. Like in replying this I need to put 4 pairs of p tag, while require only 1 pair of pre tag. But the text become hard to read for pre tag hehe :) Sorry for being lazy. But my intention is just to be more efficient.