function xmlhttpPostChgMdp(strURL) {
    var xmlHttpReq = false;
    var self = this;
    // Mozilla/Safari
    if (window.XMLHttpRequest) {
        self.xmlHttpReq = new XMLHttpRequest();
    }
    // IE
    else if (window.ActiveXObject) {
        self.xmlHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
    }
    self.xmlHttpReq.open('POST', strURL, true);
    self.xmlHttpReq.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    self.xmlHttpReq.onreadystatechange = function() {
        if (self.xmlHttpReq.readyState == 4) {
            updatepage(self.xmlHttpReq.responseText);
        }
    }
    self.xmlHttpReq.send(getquerystringChgMdp());
}

function getquerystringChgMdp() {
    var form = document.forms['form_change_mdp'];
    var mdp1 = form.mdp1.value;
    var mdp2 = form.mdp2.value;
    qstr = 'mdp1=' + escape(mdp1) + '&mdp2=' + escape(mdp2);
    // Remarque: pas de '?' avant la chane de requte
    return qstr;
}