Auto resize div 100% javascript

<script type="text/javascript">
function resize(elHeight){
    if(document.getElementById) {
        var windowheight = 0;
        var targetEl = document.getElementById('content');
        var curEl = document.getElementsByTagName('body')[0];
        var curHeight = curEl.offsetHeight;
        targetEl.style.height = (curHeight > elHeight ? curHeight:elHeight)+'px';
    }
}
var elHeight = document.getElementById('content').offsetHeight;
window.onload = function(){resize(elHeight);}
window.onresize = function(){resize(elHeight);}