Very Simple AJAX Examples With PHP (Free Code Download)

Welcome to a tutorial and examples of using AJAX with PHP. The Stone Age of the Internet is long over. If you are still doing “static HTML” or “submit a form and reload the page” – It is time to explore the power of AJAX to spice up your website.

Yes, AJAX is not as complicated as some people think. Let us walk through a few more examples – Read on!

ⓘ I have included a zip file with all the example code at the end of this tutorial, so you don’t have to copy-paste everything… Or if you just want to dive straight in.

 

 

TLDR – QUICK SLIDES

 

TABLE OF CONTENTS

 

 

QUICK NOTES

• AJAX will not work with file://, use http://.
• You can only make AJAX calls to your own website by default.
• It is possible to make a call from http://your-site.com to http://another-site.com, but this is called “cross-origins” and an advanced topic – I will leave a link below if you want to learn more.

If you spot a bug, feel free to comment below. I try to answer short questions too, but it is one person versus the entire world… If you need answers urgently, please check out my list of websites to get help with programming.

 

EXAMPLE CODE DOWNLOAD

Click here to download the source code, I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

 

 

EXAMPLE 1) AJAX TO FETCH CONTENTS

<!-- (A) HTML WRAPPER -->
<div id="wrapper"></div>
 
<!-- (B) JAVASCRIPT -->
<script>
// (B1) AJAX FETCH PHP SCRIPT
fetch("1b-content.php")
 
// (B2) RETURN SERVER RESPONSE AS TEXT
.then(res => res.text())
 
// (B3) PUT TEXT INTO WRAPPER
.then(txt => document.getElementById("wrapper").innerHTML = txt)
 
// (B4) OPTIONAL
.catch(err => console.error(err))
.finally(() => console.log("FINALLY"));
</script>

<?php
// (C) HTML CONTENT
echo "<strong>This is loaded with AJAX.</strong>";

This is the “full version” of the introduction snippet. Pretty self-explanatory, but for those who are lost:

• (B1) fetch(URL) Make an AJAX call to the specified script.
• (B2) .then(res => res.text()) Return the server response as plain text. Yep, we can also return the results as JSON, binary data, or even a raw data stream.
• (B3) .then(txt => ...) Deal with the fetch results. In this example, we simply put it into <div id="wrapper">.
• (B4) .catch(err => ...) Optional, deal with errors.
• (B4) .finally(() => ...) Optional, this will run regardlessly after then() or catch().

If you think this looks familiar, you are right. An AJAX fetch() works just like a try-catch-finally block.

P.S. If you do not already know about arrow functions () => {}, I will do a quick explanation at the bottom.

 

 

EXAMPLE 2) AJAX SUBMIT FORM

<!-- (A) HTML FORM -->
<form id="myForm" onsubmit="return ajaxpost()">
  <input type="text" name="name" required value="Jon Doe">
  <input type="email" name="email" required value="jon@doe.com">
  <input type="submit" value="Go!">
</form>
 
<!-- (B) JAVASCRIPT -->
<script>
function ajaxpost () {
  // (B1) GET FORM DATA
  var form = document.getElementById("myForm"),
      data = new FormData(form);
  data.append("KEY", "VALUE"); // add more data if you want
 
  // (B2) AJAX POST
  fetch("2b-form.php", { method:"POST", body:data })
  .then(res => res.text())
 
  // (B3) RESULTS
  .then(txt => {
    console.log(txt);
    // do something with txt
  });
  return false;
}
</script>

<?php
// (C) ECHO SUBMITTED FORM DATA
print_r($_POST);

What is so cool about using AJAX to submit forms? It will not reload the entire page.

• (A) Use Javascript to handle the form submission <form onsubmit="return ajaxpost()">.
• (B1) Collect the form data
  • We feed the entire HTML form into var data = new FormData(FORM). This will automatically adapt the form fields NAME : VALUE into data.
  • If you want to add more data, use data.append(KEY, VALUE).
• (B2) Same old fetch(), but we POST the data to the server – { method:"POST", body:data }
• (C) Do your own processing in your project, then respond with “OK” or “ERROR”.
• (B3) Deal with the results. Take note, we return false to prevent the default form submission and reloading the page.

P.S. For GET requests, simply append a query string behind the URL – SCRIPT.PHP?KEY=VALUE&KEY=VALUE

 

 

EXAMPLE 3) SENDING JSON DATA (ARRAYS & OBJECTS)

// (A) ARRAY DATA
var arr = ["FOO", "BAR"];
var data = new FormData();
data.append("DATA", JSON.stringify(arr));
 
// (B) SEND TO SERVER
fetch("3b-send-json.php", { method:"POST", body:data })
.then(res => res.text())
.then(txt => console.log(txt));

<?php
// (C) JSON DECODE BACK INTO ARRAY
$received = json_decode($_POST["DATA"]);
print_r($_POST);
print_r($received);

To send arrays and objects in AJAX, a common way is to JSON encode-decode it:

1. Use JSON.stringify() to turn an array/object into a JSON encoded string.
2. POST the JSON encoded string to the server.
3. Then in PHP, use json_decode() to turn the string back into an array/object.

 

EXAMPLE 4) FETCHING JSON DATA

<?php
// (A) OUTPUT JSON ENCODED STRING
$arr = ["HELLO", "WORLD"];
echo json_encode($arr); 

// (B) FETCH FROM SERVER
fetch("4a-fetch-json.php")
 
// (C) PARSE JSON DATA
.then(res => res.json())
.then(data => { console.log(data); });

1. The PHP server-side will output a JSON encoded array – json_encode($ARRAY).
2. fetch(SCRIPT.PHP) Get data from the server.
3. JSON decode it back into an array – .then(res => res.json()).

 

 

EXAMPLE 5) XML HTTP REQUEST

// (A) FORM DATA
var data = new FormData();
data.append("KEY", "VALUE");
 
// (B) AJAX REQUEST
var xhr = new XMLHttpRequest();
xhr.open("POST", "2b-form.php");
xhr.onload = function () {
  console.log(this.status); // HTTP RESPONSE CODE
  console.log(this.response); // SERVER RESPONSE TEXT
};
xhr.send(data);

If you have been poking around the Internet, you will notice that some tutorials do AJAX calls differently.

• Yes, XMLHttpRequest() is also used to do AJAX. It still works, but this is the “traditional way”.
• fetch() is the modern and recommended way.

 

 

ARROW FUNCTIONS!?

Here’s a quick crash course for the complete newbies.

// (A) YOU ALREADY KNOW THIS
function twice (num) { return num * 2; }
  
// (B) WE CAN ALSO DO THIS
var twice = function (num) { return num * 2; };
 
// (C) IN MODERN JS, WE CAN SHORTHAND IT AS AN "ARROW FUNCTION"
var twice = (num) => { return num * 2; };
 
// (D) WE CAN FURTHER SIMPLIFY "SINGLE PARAMETER & RETURN" FUNCTIONS
var twice = num => num * 2;

// (E) RUN!
console.log(twice(123));

 

COMPATIBILITY CHECKS

• Arrow Functions – CanIUse
• Fetch – CanIUse

Beware if you have to support ancient browsers. Fallback to use XMLHttpRequest() and define functions in the “old school way”  – function(){}.

 

LINKS & REFERENCES

• XMLHttpRequest – MDN
• FormData – MDN
• Fetch – MDN
• HTTP Status Codes – Wikipedia
• Submit HTML Form Without Refreshing Page – Code Boxx
• Cross-Origin Fetch In Javascript – Code Boxx

 

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