Hvordan bruger man onLoad hvis det ikke skal stå i body tagget?

Hvorfor laver dette script fejl ( i den nederste onload linie)

<script type="text/javascript">

// onresize for ns4
var origWidth, origHeight;
if (document.layers) {
origWidth = window.innerWidth; origHeight = window.innerHeight;
window.onresize = function() { if (window.innerWidth != origWidth || window.innerHeight != origHeight) history.go(0); }
}

var cur_lyr;    // holds id of currently visible layer
function swapLayers(id) {
if (cur_lyr) hideLayer(cur_lyr);
showLayer(id);
cur_lyr = id;
}

function showLayer(id) {
var lyr = getElemRefs(id);
if (lyr && lyr.css) lyr.css.visibility = "visible";
}

function hideLayer(id) {
var lyr = getElemRefs(id);
if (lyr && lyr.css) lyr.css.visibility = "hidden";
}

function getElemRefs(id) {
var el = (document.getElementById)? document.getElementById(id): (document.all)? document.all[id]: (document.layers)? document.layers[id]: null;
if (el) el.css = (el.style)? el.style: el;
return el;
}

onload = showLayer('lyr1');

</script>



<div id="lyr1">
Dette lag skal vises til at starte med
</div>