I search my TypeScript code a lot and finally got tired of using awk, grep, and friends to filter out irrelevant files. Here's a definition for .ts files and .d.ts files to help you out.
Put this in your .ackrc file (or use those switches at the command line).
Now you can search just your .ts files without also searching compiled .js and .d.ts files with
ack --ts --notsdef mySearch.
More information in the ack manpage.