Add a "Hook" to All Ajax Requests on a Page

Add a hook to all AJAX requests on a page

Inspired by aviv's answer, I did a little investigating and this is what I came up with.

I'm not sure that it's all that useful as per the comments in the script and of course will only work for browsers using a native XMLHttpRequest object.

I think it will work if javascript libraries are in use as they will use the native object if possible.

function addXMLRequestCallback(callback){
    var oldSend, i;
    if( XMLHttpRequest.callbacks ) {
        // we've already overridden send() so just add the callback
        XMLHttpRequest.callbacks.push( callback );
    } else {
        // create a callback queue
        XMLHttpRequest.callbacks = [callback];
        // store the native send()
        oldSend = XMLHttpRequest.prototype.send;
        // override the native send()
        XMLHttpRequest.prototype.send = function(){
            // process the callback queue
            // the xhr instance is passed into each callback but seems pretty useless
            // you can't tell what its destination is or call abort() without an error
            // so only really good for logging that a request has happened
            // I could be wrong, I hope so...
            // EDIT: I suppose you could override the onreadystatechange handler though
            for( i = 0; i < XMLHttpRequest.callbacks.length; i++ ) {
                XMLHttpRequest.callbacks[i]( this );
            }
            // call the native send()
            oldSend.apply(this, arguments);
        }
    }
}

// e.g.
addXMLRequestCallback( function( xhr ) {
    console.log( xhr.responseText ); // (an empty string)
});
addXMLRequestCallback( function( xhr ) {
    console.dir( xhr ); // have a look if there is anything useful here
});

Is it possible to listen all Ajax calls?

Try this:

$(document).ajaxStart(function () { 
  console.log('Request Initiated'); 
}); 
$(document).ajaxComplete(function () { 
  console.log('Request Complete'); 
});

How to intercept all AJAX requests made by different JS libraries

This type of function hooking is perfectly safe and is done regularly on other methods for other reasons.

And, the only performance impact is really only one extra function call for each .open() plus whatever code you execute yourself which is probably immaterial when a networking call is involved.

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In IE, this won't catch any code that tries to use the ActiveXObject control method of doing Ajax. Well written code looks first for the XMLHttpRequest object and uses that if available and that has been available since IE 7. But, there could be some code that uses the ActiveXObject method if it's available which would be true through much later versions of IE.

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In modern browsers, there are other ways to issue Ajax calls such as the fetch() interface so if one is looking to hook all Ajax calls, you have to hook more than just XMLHttpRequest.

Ajax request not save form data when add woocommerce hook

I found a solution, we needed to add array with var to the hook &$errors &$user

add_action( 'woocommerce_save_account_details_errors', array( &$errors, &$user ), 1, 10 );

add_action( 'wp_ajax_save_account_details', 'save_account_details' );

function save_account_details( $user_id ) {
  if (trim($_POST['account_first_name']) == '') {
      wc_add_notice("<b>Nome</b> è un campo obbligatorio", "error");
      $response = wc_print_notices();
    } else if ( isset( $_POST['account_first_name'] ) ) {
      wc_add_notice("Modifiche salvate con successo", "success");
      $response = wc_print_notices();
    }
    echo json_encode($response);
    exit();
}

React Hooks - Making an Ajax request

You could create a custom hook called useFetch that will implement the useEffect hook.

If you pass an empty array as the second argument to the useEffect hook will trigger the request on componentDidMount. By passing the url in the array this will trigger this code anytime the url updates.

Here is a demo in code sandbox.

See code below.

import React, { useState, useEffect } from 'react';

const useFetch = (url) => {
  const [data, setData] = useState(null);

  useEffect(() => {
    async function fetchData() {
      const response = await fetch(url);
      const json = await response.json();
      setData(json);
    }
    fetchData();
  }, [url]);

  return data;
};

const App = () => {
    const URL = 'http://www.example.json';
    const result = useFetch(URL);
 
    return (
      <div>
        {JSON.stringify(result)}
      </div>
    );
}

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