YSK: Most customer service live-chat agents can see what you're typing as you're typing it. If you type something out and then erase it before hitting send, they probably still saw it.
from /r/YouShouldKnow
YSK：大多数客服即时聊天代理可以在你打字的时候看到你在打什么。如果你打出一些东西，然后在点击发送前擦掉，他们可能还是看到了。