How To Use Javascript Variable In Php

Integrating JavaScript and PHP might seem a bit confusing at first, since they are two completely different programming languages. However, with the right approach, one can use JavaScript variables within PHP. This tutorial will show you how to do just that.

Method 1: Using AJAX

The most common way to use a JavaScript variable in PHP is by using AJAX (Asynchronous JavaScript and XML). AJAX is a technique for creating fast, dynamic and interactive web applications. It allows you to update parts of a web page without reloading the entire page.

Here’s an example of how to use JavaScript variables in PHP using AJAX:

Step 1: Create an HTML form

First, create a simple HTML form that takes user input and has a button to submit the information:

    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JS Variable to PHP</title>


    <form>
        <label for="username">Username:</label>
        <input type="text" id="username" name="username">
        <button type="button" onclick="sendData()">Submit</button>
    </form>
    <p id="result"></p>

    <script src="script.js"></script>

Step 2: Send the JavaScript variable using AJAX

Create a new JavaScript file, script.js, and write the following code to send the data using AJAX:

function sendData() {
    let username = document.getElementById("username").value;

    // Create an XMLHttpRequest object
    let xhttp = new XMLHttpRequest();

    // Define what happens on successful data submission
    xhttp.onreadystatechange = function() {
        if (this.readyState === 4 && this.status === 200) {
            document.getElementById("result").innerHTML = this.responseText;
        }
    };

    // Send the request and data to the PHP file
    xhttp.open("POST", "process.php", true);
    xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    xhttp.send("username=" + username);
}

Step 3: Process the JavaScript variable in PHP

Create a new PHP file, process.php, and write the following code to process the JavaScript variable:

<p>Now when you submit the form, the JavaScript variable will be sent to the PHP file, and the output will be displayed without reloading the page.</p>

    <h2>Method 2: Using a Hidden Input Field</h2>
    <p>Another method to use a JavaScript variable in PHP is by using a hidden input field in the form. This approach is simpler, but it requires a page refresh.</p>

    <p>Modify the HTML form and add a hidden input field:</p>

[sourcecode]
<form method="POST">
    <label for="username">Username:</label>
    <input type="text" id="username" name="username">
    <input type="hidden" id="jsVar" name="jsVar">
    <button type="submit">Submit</button>
</form>

Add JavaScript code to set the value of the hidden input field before submitting the form:

document.querySelector('form').addEventListener('submit', function(e) {
    let jsVariable = "Hello from JavaScript!";
    document.getElementById('jsVar').value = jsVariable;
});

Now, in your PHP code, you can access the JavaScript variable using the $_POST method:

These are two methods to use JavaScript variables in PHP. Keep in mind that while the first method (using AJAX) is more complex, it provides a better user experience by not requiring a page reload.