javascript - readyState is not changing to 4 -


this question has answer here:

i making chat application.in chat application, there "send" button, on clicking call javascript function.

    function sendmessage() {     var message = document.getelementbyid('messagebox');     var currentuser = document.getelementbyid('username').value;      if(trim(message.value) != '' && trim(currentuser) != '')     {         params = "mode=sendandretrievenew"+                  "&name="+encodeuricomponent(currentuser)+                  "&message="+encodeuricomponent(message.value);         message.value="";          xmlhttpgetmessages.open("post",chaturl,true);         xmlhttpgetmessages.setrequestheader("content-type","application/x-www-form-urlencoded");         xmlhttpgetmessages.onreadystatechange = sendmessages();         xmlhttpgetmessages.send(params);     } }

here variable xmlhttpgetmessages object of xmlhttprequest. chaturl variable contains name of php file. following snippet runs in php file.

    if($mode == 'sendandretrievenew') {     $name = $_post['name'];     $message = $_post['message'];     //$id = $_post['id'];      if($name != '' && $message != '')     {         $chat->postmessages($name,$message);     } }

the postmessages($name,$message); follows:

public function postmessages($name, $message)     {         $name = $this->mysqli->real_escape_string($name);         $message = $this->mysqli->real_escape_string($message);          $query = 'insert chat(posted_on, user_name, message) values ( now(), " ' . $name . ' " , " '. $message .' " )';          $result = $this->mysqli->query($query);     }

the sendmessages() function as:

    function sendmessages() {     if(xmlhttpgetmessages.readystate == 4)     {         if(xmlhttpgetmessages.status = 200 || xmlhttpgetmessages.status == 304)             alert("send message.check database");         else             alert("in else of inner if");     }     else         alert("in else of outer if "+xmlhttpgetmessages.readystate); }

the readystate value changes 0 1, evident last alert();. how make it's value change 4.

after reading first answer changed xmlhttpgetmessages.onreadystatechange = sendmessages(); xmlhttpgetmessages.onreadystatechange = sendmessages , worked. last alert() sendmessages() executed , shows value of readystate changing 2,3 , inner if executed. how function called 3 times? know there answer in comment, didn't understand. pls help. newbie in ajax.

this incorrect:

    xmlhttpgetmessages.onreadystatechange = sendmessages();                                                         ^^

the () means javascript executing sendmessages function right , there. function returns nothing, you're setting onreadystatechange callback null.

it should just

    xmlhttpgetmessages.onreadystatechange = sendmessages;                                                         ^---note

which assigns function itself, not results.


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