var currentHash = '';
function setHash(string){
    if(window.location.hash!=string){
        window.location.hash = string;
     }
}

function getHash() {
    var index = window.location.href.indexOf('#');
    if (index != -1) {
        return window.location.href.substring(index +1);
    }
    return '';
}


function hashListen(){

    if(currentHash != window.location.hash){
    alert(window.location.hash);
        currentHash = window.location.hash;
        var obj = document["usage"] || document.getElementById("usage");        
        if (obj) {
            obj.hashChange(getHash());
        }
    }

}

//setInterval(hashListen, 50);