Stanford JavaScript crypto library:
Example:
<script type="text/javascript" src="js/sjcl.js"></script>
<script type="text/javascript" src="js/sha1.js"></script>
<script type="text/javascript" src="js/sha256.js"></script>
<script type="text/javascript">
/*** SHA1 */
var bitArray = sjcl.hash.sha1.hash("message");
var digest_sha1 = sjcl.codec.hex.fromBits(bitArray); // Convert from a bitArray to a hex string.
/*** SHA256 */
var bitArray = sjcl.hash.sha256.hash("message");
var digest_sha256 = sjcl.codec.hex.fromBits(bitArray);
</script>
The hash functions available are: