How to rename group of files?

I am giving a simple shell script, for renaming a group of files in the current directory.In the script, i have renamed all .jsk files to .txt files.

for filename in *.jsk
do
mv $filename `basename $filename jsk`txt
done

Explanation:
1.In the for statement, i am finding out all the .jsk extension files.
2.In the mv statement, i am using basename command to strip the jsk extension.