This is a way to count lines in JavaScript files. It will count the comments (multiline with /*, *, and */ as well as single line //). It then outputs the number of lines, number of comment lines, and number of code lines

linecount.sh

printf "%25s %6s %6s %10s\n" "Filename" "Lines" "Code" "Comments" && \
find -name "*.js" -exec awk ' \
    /^[ \t]*([\/]*\*|\/\/)/ {comments++} \
    /^[ \t]*$/ {blank++} \
    END{printf "%25s %6s %6s %10s\n",FILENAME,FNR,FNR-comments-blank,comments} \
' {} \;