var _isInitialLoad = true;

function pageLoad(sender, args) {
    if (_isInitialLoad) {
        _isInitialLoad = false;
        // Go get button that needs the postback 
        // Have to get parent div first
        var parentDiv = document.getElementById("HiddenButton");

        //alert(parentDiv);
        // Get child button
        var ourButton = parentDiv.getElementsByTagName("input");
        ourButton = ourButton[0].id;
        
        var button = document.getElementById(ourButton);
        button.click(); 
        
    }
}