How to add page number for every page in laravel dompdf?

Try this one.

<style>
   .pagenum:before {
        content: counter(page);
    }
</style>
<body>

    <span class="pagenum"></span>

    <table>
        <tr>
          <th>header1</th>
          <th>header2</th>
          <th>header3</th>
     </tr>
     <tr>
         <td>content-row-1</td>
          <td>content-row-1</td>
         <td>content-row-1</td>
     </tr>
     <tr>
        <td>content-row-2</td>
        <td>content-row-2</td>
        <td>content-row-2</td>
     </tr>
    </table>
</body>

Follow below steps to achieve it:
- Enable DOMPDF_ENABLE_PHP from /config/dompdf.php
- Publish vendor file via php artisan vendor:publish command
- Pass $pdf object from controller:
- Add below code inside the view file:

<script type="text/php">
    if ( isset($pdf) ) {
        $font = Font_Metrics::get_font("helvetica", "bold");
        $pdf->page_text(72, 18, "Header: {PAGE_NUM} of {PAGE_COUNT}", $font, 6, array(0,0,0));
    }
</script> 

You can get more idea from Page count and page number