Sending JSON to PHP file and Recieving Response in JS

Question

I have looked at many other questions on here and I have tried many different methods but none seem to work.

Heres my javascript file

function sendData() {
 var jsondata;
 var j = {"pub_id":"'+pid+'","a_type":"'+a_t'","p_domain":"'+domain+'"}
 var str_j = JSON.stringify(j);
 var xhr = new XMLHttpRequest();
 xhr.open("POST", "https://ads.schlarman.org/zz.php", !0);
 xhr.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
 xhr.onreadystatechange = function() {
 if (xhr.readyState === 4 && xhr.status === 200) {
 jsondata = JSON.parse(xhr.responseText);
 console.log(jsondata);
 }
 }
}
sendData();

then zz.php

<?php 
 header('Content-type: application/json');
 $json = file_get_contents('php://input');
 $json_decode = json_decode($json, true);
 $json_encode = json_encode($json_decode);
 echo $json_encode;
?>

• Nick: How does it fail exactly? Would love a little more detail about the error(s) you're getting.
• StackSlave: Invalid JSON to begin with.
• Tim Morton: $json_decode = json_decode($json, true); strikes me as kind of an odd thing to do.
• Tristan Schlarman: @snapjs I didnt get any response from the PHP file, not even an error
• Tristan Schlarman: @PHPglue Still new to all of this and I was reading and thats how it was said to be done. I is including Javascript Varibles

Answer 1

If at all possible, build your json strings from actual javascript arrays/objects

var j = {"pub_id":"'+pid+'","a_type":"'+a_t'","p_domain":"'+domain+'"};

could & probably should be

var j = {"pub_id": pid, "a_type": a_t, "p_domain": domain};

Also, try adding the following header to your php

Access-Control-Allow-Origin: *

More info here: https://enable-cors.org/server.html

• Tristan Schlarman: Thanks! I finally got a response from the zz.php file. Does this open up security issue though?
• admcfajn: You're very welcome. As for a security issue, yes. You might want to use: Access-Control-Allow-Origin: http://yourdomain.com.