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How to Post Form Data Using Ajax, Javascript, and PHP

Updated on March 12, 2015

In this blog I'll demonstrate how to send form data using AJAX through a POST request from an HTML and JavaScript page to a PHP form handler page, then get the results using AJAX and display them on the original page. Our form will contain both uploaded files and regular input.

form.html

First I'll put the div where we're going to put our response from the handler page:

Then we'll need our html form. This is a basic form with a first name, last name, and picture input.

If we wanted to upload multiple images, we would just add "multiple" anywhere in the file input element below.

Now we need to add the javascript that will take care of the form submit using ajax.

First we get the form element by its ID and prevent the default form submit from occurring.

We initialize a variable ajax that will handle sending the request to the PHP form handler page.

We initialize this variable in different ways depending on whether the client's browser supports XMLHttpRequest or not.

Then we have our onreadystatechange function, which will detect when the request has been processed by the PHP page and the response is ready.

If the readyState is 4 (request processed and response ready) and the status is 200 (no errors, status is "OK") then we fetch the response as a string and put it in the success div at the top.

Next we formulate our FormData object, which is used to send our form data to the PHP page.

We fetch the file element by getting the first element in the files array of the upload element of our form.

If we had multiple files to upload, we would iterate through all of the elements in the files array and append all of them.

For the names we just fetch the value of the input fields.

We then send the data to the form handler page using POST.

formHandler.php

Now we're going to put the form handler code in our formHandler.php file. The main difference between using ajax to submit the form and using the built-in form submit is that instead of using $_POST to get our form data, we're going to use $_REQUEST. The $_FILES superglobal will still be used to access our uploaded file. So here's the PHP form handling:

Fetch the user's name:

If we had only one image:

If we uploaded multiple images:

And all this does is echo out the input they gave. This text will be displayed above our form as soon as the form submission has been handled.


Congratulations! You can now do a form submit using AJAX and PHP.

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