How To Get Javascript Variable Value In Php

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PHP Interactionn working with web development, you might often encounter situations where you need
to pass a value from JavaScript to PHP. In this blog post, we will learn how to get a JavaScript
variable’s value in PHP using a simple example.

Understanding JavaScript and PHP Interaction

It’s essential to understand that JavaScript and PHP are two different programming languages
that run in different environments. JavaScript is a client-side language that runs inside a
user’s browser, while PHP is a server-side language that runs on the server.

Due to this distinction, you cannot directly access JavaScript variable values in PHP code.
However, there is a workaround: by using AJAX (Asynchronous JavaScript and XML) or submitting
HTML forms, you can pass data from JavaScript to PHP. In this tutorial, we will focus on using AJAX.

Using AJAX to Pass JavaScript Variable Value to PHP

Here’s a step-by-step guide on how to pass a JavaScript variable value to PHP using AJAX:

  1. Create an HTML form to get user input
  2. Use JavaScript to capture the input value
  3. Send an AJAX request to the PHP file
  4. Retrieve the JavaScript variable value in PHP

1. Create an HTML form to get user input

First, create a simple HTML form with an input field and a button. The input field will
capture the value that the user enters, while the button will trigger the JavaScript function
to send an AJAX request. 

</strong>
    <pre><code>&lt;form&gt;
    &lt;input type="text" id="txt_value" placeholder="Enter a value"&gt;
    &lt;button type="button" onclick="sendValueToPhp()"&gt;Submit&lt;/button&gt;
&lt;/form&gt;</code></pre>
    <strong>

2. Use JavaScript to capture the input value

Next, create a JavaScript function that captures the value from the input field and
stores it in a variable. 

</strong>
    <pre><code>function sendValueToPhp() {
    let inputValue = document.getElementById("txt_value").value;
}</code></pre>
    <strong>

3. Send an AJAX request to the PHP file

Now that we have the input value in a JavaScript variable, let’s send it to a PHP file using
an AJAX request. You can use the XMLHttpRequest object or the Fetch API to create
an AJAX request.

In this example, we will use the Fetch API to send a POST request to a file named
process_value.php. 

</strong>
    <pre><code>function sendValueToPhp() {
    let inputValue = document.getElementById("txt_value").value;

    fetch("process_value.php", {
        method: "POST",
        headers: {
            "Content-Type": "application/x-www-form-urlencoded"
        },
        body: "value=" + inputValue
    })
        .then(response =&gt; response.text())
        .then(data =&gt; console.log(data));
}</code></pre>
    <strong>

4. Retrieve the JavaScript variable value in PHP

Finally, create the process_value.php file to receive the AJAX request and
retrieve the JavaScript variable value in PHP. 

</strong>
    <pre><code>&lt;?php
$value = $_POST["value"];
echo "Received value: " . $value;
?&gt;</code></pre>
    <strong>

In the PHP file, we use the $_POST superglobal array to access the value sent via
the AJAX request. After retrieving the value, you can use it for further processing as required.

Conclusion

In this blog post, we learned how to pass a JavaScript variable value to PHP using an
AJAX request. Remember that you cannot directly access JavaScript variable values in PHP
code, but by using AJAX or HTML forms, you can work around this limitation.