hi, thank you very much for your quick answer. 
let me ask one more thing.
when i change my code in this way,
<a href="http://twitter.com/intent/tweet?via=jooddang" class="my_class" id="twitter-share-button">gogo</a>
<script>
twttr.events.bind('click', function(event){alert('clicked');});
it works beautifully.
i guess twttr recognizes id="twitter-share-button" and its href attribute, right?
then, i wanna get a complete list of data i can get from bind function.
from the link you gave me above (https://dev.twitter.com/docs/intents/events) , i can guess i could get data like “intent_event.data.source_tweet_id”, but i couldn’t find a complete list of data.
for example, in this code,
the alert box returns null for tid. when i try event.data.tweet_id instead of event.data , it gives me javascript error. (Uncaught TypeError: Cannot read property ‘tweet_id’ of null from chrome console).
in short, let me know which kinds of data i can get from bind function…
thank you very much again!