How can I write to the console in PHP?

Firefox

On Firefox you can use an extension called FirePHP which enables the logging and dumping of information from your PHP applications to the console. This is an addon to the awesome web development extension Firebug.

• http://www.studytrails.com/blog/using-firephp-in-firefox-to-debug-php/

Chrome

However if you are using Chrome there is a PHP debugging tool called Chrome Logger or webug (webug has problems with the order of logs).

More recently Clockwork is in active development which extends the Developer Tools by adding a new panel to provide useful debugging and profiling information. It provides out of the box support for Laravel 4 and Slim 2 and support can be added via its extensible API.

Using Xdebug

A better way to debug your PHP would be via Xdebug. Most browsers provide helper extensions to help you pass the required cookie/query string to initialize the debugging process.

• Chrome - Xdebug Helper
• Firefox - The easiest Xdebug
• Opera - Xdebug
• Safari - Xdebug Toggler

If you're looking for a simple approach, echo as JSON:

<script>
    console.log(<?= json_encode($foo); ?>);
</script>

Or you use the trick from PHP Debug to console.

First you need a little PHP helper function

function debug_to_console($data) {
    $output = $data;
    if (is_array($output))
        $output = implode(',', $output);

    echo "<script>console.log('Debug Objects: " . $output . "' );</script>";
}

Then you can use it like this:

debug_to_console("Test");

This will create an output like this:

Debug Objects: Test