将网络请求从同步转换为异步（PHP / Javascript）

Question

I actually use a php script for an advertising network, but the code that publisher will use is synchronous. Now, I want that the script will load asynchronous.

Do I need to change all the PHP/Javascript code ? OR there is a trick to use (javascript library...)

Thank you for your help !

Answer 1

Synchronous/Asynchronous depends on the client side. Unless very particular exceptions.

So focus on Javascript code .: https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Synchronous_and_Asynchronous_Requests

EDIT Example: send a file to the console log

This is the simplest usage of asynchronous XMLHttpRequest.

var xhr = new XMLHttpRequest();
xhr.open("GET", "http://bar/foo.txt", true/*ASYNCHRONOUS*/);

/* here is registered what-to-do once xhr is 'done': 
it can happens anywhen, it is Asynchronous: */
    xhr.onload = function (e) {
      if (xhr.readyState === 4) {
        if (xhr.status === 200) {
          console.log(xhr.responseText);
        } else {
          console.error(xhr.statusText);
        }
      }
    };
    xhr.onerror = function (e) {
      console.error(xhr.statusText);
    };
    xhr.send(null);

A contrario , this is synchronous :

var request = new XMLHttpRequest();
request.open('GET', 'http://...', false/*ASYNCHRONOUS=false, it is SYNCHRONOUS)*/
request.send(null);
/*anything else is stopped around, one thread working only:request*/

   /*once it is done, the next line is executed. This is:*/
    if (request.status === 200) {
      console.log(request.responseText);
    }

So get where JS Sync method is done in your JS code and change one for the other.

Answer 2

I'm not completely sure, but i think jQuery Ajax call is what yo want. http://api.jquery.com/jquery.ajax/

Here is sample ajax call:

$.ajax({
 url: formURL,
 type: "POST",
 data: postData,
 beforeSend: function() {
    //this code always run Ususaly UI changes
 },
 success: function(data, textStatus, jqXHR) {
    //var result = JSON.parse(data);
 },
 error: function(jqXHR, textStatus, errorThrown) {
    //if ajax fails 
 },
 complete: function(response) {
   // this code always run Ususaly UI changes
 }
});

Also since PHP always returns string, for success you can simply use:

 "echo $string;" 

If you want to return an array you should:

"echo json_encode($array);"

For the error part it is better to force PHP to return error somethng like:

header('HTTP/1.1 422 Unprocessable Entity');
header('Content-Type: application/json; charset=UTF-8');
die(json_encode($errors));
exit;