PHP

alert in php

echo '<script>alert("Message")</script>';

alert in php

// This is in the PHP file and sends a Javascript alert to the client
$message = "Something";
echo "<script type='text/javascript'>alert('$message');</script>";

echo alert php

echo "<script>alert('error : ".$error."');</script>";

alert a php variable

echo '<script type="text/javascript">alert("'.$error.'");</script>';

alerta con php

echo '<script language="javascript">alert("juas");</script>';