JavaScript Prompt Box Cancel Button?
问题 I have a JavaScript function as follows: function popup(username) { var req = createAjaxObject(); var message = prompt("Message:",""); if(message != ""){ req.onreadystatechange = function() { if (req.readyState == 4) { alert(req.responseText); } } req.open('POST','getmessage.php',true); req.setRequestHeader("Content-type","application/x-www-form-urlencoded"); req.send("username=" + username +"&message="+message); } else { alert("Please enter a message"); } } When the Cancel button is hit, the