alert()은 다이알로그 박스에 메시지를 나타낼 때 사용
confirm()은 메시지를 나타내고 확인을 할 때 사용(OK/Cancel)
prompt()는 메시지를 나타내고 문자열의 입력을 받을 때 사용
<예>
<HTML>
<HEAD><TITLE>Alerts, Confirmations, and Prompts</TITLE>
</HEAD>
<BODY>
<H1>Alerts, Confirmations, and Prompts</H1>
<HR>
Use the buttons below to test dialogs in JavaScript.
<HR>
<FORM NAME="winform">
<INPUT TYPE="button" VALUE="Display an Alert"
onClick="window.alert('This is a test alert.'); ">
<P><INPUT TYPE="button" VALUE="Display a Confirmation"
onClick="temp = window.confirm('Would you like to confirm?');
window.status=(temp)?'confirm: true':'confirm: false'; ">
<P><INPUT TYPE="button" VALUE="Display a Prompt"
onClick="var temp = window.prompt('Enter some Text:','This is the default value');
window.status=temp; ">
</FORM>
<BR>Have fun!
<HR>
</BODY>
</HTML>
