java script to replace words starting and ending with tild(~) symbol in a text area with the word highlighted yellow.

Hi, I have an issue with highlighting text in a text area. I am designing a page to send email. currently the email subject and body is having a predefined format where the user needs to enter appropriate text for the portion preceded and succeded with tild(~) symbol. This is applicable in the subject line and the email body.

AS per new requirement we have to replace all the occurence of such words and replace with highlighted text.

for example: The script should findout all the occurence of the words like ~anyword~ and replace it with anyword highlighted yellow.

this is bit urgent. could anyone help me on this.

Thank you for your support.