Balise de type span, div ???

document.getElementById('toto').innerHTML;

document.getElementById('toto').innerHTML = "ce que tu veux";

var div = document.getElementById('toto').innerHTML;

<div id="tot">
<?php
$sql = mysql_query("ta requette");
$tab = mysql_fetch_array($rsql);
echo $tab['champ_de_ta_bdd_contennant_ton_info'];
?>
</div>

<script>
var recup_txt = <?php echo $tab['champ_de_ta_bdd_contennant_ton_info']; ?>;
</script>