function calculateTotalHeightMinusElement(excludeElementClass)
{
var bodyChildren = (document.getElementsByTagName('body')[0]).children;
var totalHeight = 0;
for (var i = 0; i < bodyChildren.length; i++) {
totalHeight = totalHeight + bodyChildren[i].offsetHeight;
}
var excludedElementHeight = document.getElementsByClassName(excludeElementClass)[0].offsetHeight;
var finalHeight = totalHeight - excludedElementHeight;
alert("Total height: " + finalHeight);
}
document.addEventListener("DOMContentLoaded", function(event) {
calculateTotalHeightMinusElement("myDivClass");
});