javascript - Send JS variable to PHP -

i take value using getelementbyid() , pass variable on php.

<script> function addmachine() {   var ip = document.getelementbyid('iptextbox').value;   document.getelementbyid('iptextbox').submit; } <\script> 

the html looks that

<div class="container">      <button type="button" class="btn btn-info btn-lg" data-toggle="modal" data-target="#addmachine">      <div class="modal fade" id="addmachine" role="dialog">         <div class="modal-dialog modal-sm">             <div class="modal-content">                 <div class="modal-header">                     <button type="button" class="close" data-dismiss="modal">&times;</button>                     <h4 class="modal-title">add new machine</h4>                 </div>                 <div class="modal-body">                     <label>insert machine ip<input id="iptextbox"></input></label>                 </div>                 <div class="modal-footer">                      <button type="button" class="btn btn-default" data-dismiss="modal" onclick="addmachine()">add</button>                 </div>             </div>         </div>     </div> <\div> 

i don't have ideas on how pass php variable.

php backend language used render html , send client on page load. , javascript client side language. if want send variables js php, sending information client server without page reload, need use ajax:

ajax stands "asynchronous javascript , xml". although name includes xml, json more used due it's simpler formatting , lower redundancy. ajax allows user communicate external resources without reloading webpage. stackoverflow's documentation on javascript ajax

• with ajax

i have made post on documentation page, here is. hope helps understand how works.

this function runs ajax call using allowing send parameters (object) file (string) , launch callback (function) when request has been ended.

function ajax(file, params, callback) {    var url = file + '?';    // loop through object , assemble url   var notfirst = false;   (var key in params) {     if (params.hasownproperty(key)) {       url += (notfirst ? '&' : '') + key + "=" + params[key];     }     notfirst = true;   }    // create ajax call url parameter   var xmlhttp = new xmlhttprequest();   xmlhttp.onreadystatechange = function() {     if (xmlhttp.readystate == 4 && xmlhttp.status == 200) {       callback(xmlhttp.responsetext);     }   };   xmlhttp.open('get', url, true);   xmlhttp.send(); } 

here's how use it:

ajax('cars.php', {type:"volvo", model:"300", color:"purple"}, function(response) {   // add here code executed when data comes page         // example console.log(response) show ajax response in console }); 

and following shows how retreive url parameters in cars.php:

if(isset($_request['type'], $_request['model'], $_request['color'])) {   // set, can use them !   $response = 'the color of car ' . $_request['color'] . '. ';   $response .= 'it ' . $_request['type'] . ' model ' . $_request['model'] . '!';   echo $response; } 

if had console.log(response) in callback function result in console have been:

the color of car purple. volvo model 300!

• with html form

in html page have include form

<form action="get_data.php" method="get">   name: <input type="text" name="name"><br>   e-mail: <input type="text" name="email"><br>   <input type="submit"> </form> 

and in get_data.php (the target file) you'll have write:

<?php echo $_get["name"]; echo $_get["email"]; 

this second method redirect user get_data.php, personnaly don't , prefer ajax efficiency.