var cerrarVentana = true;

function cTrim(cad, car) {
    var i;
    var cad2 = "";
    for (i = 0; i < cad.length; i++) {
        if (cad.charAt(i) != car) {
            cad2 += cad.charAt(i);
        }
    }
    return cad2;
}

function CheckKeys() {
    if ((event.keyCode >= 97 && event.keyCode <= 122) || (event.keyCode >=65 && event.keyCode <=90)) {
        event.keyCode = 0;
    }
}

function cerrar() {
    window.close(this);
}

function darFoco(el) {
    el.focus();
}

function regresar() {
    cerrarVentana = false;
    history.back();
}

function imprimir() {
    window.print();
}

function llamarPagina(pagina) {
    cerrarVentana = false;
    document.location.href = pagina;
}

function nada() {
    return;
}

function enviarDatos(form) {
    cerrarVentana = false;
    form.submit();
}

function pausa(millis) {
    date = new Date();
    var curDate = null;
    do {
        var curDate = new Date();
    }
    while(curDate-date < millis);
}

function cerrarBorwser() {
    if (cerrarVentana) {
        salir();
        pausa(1000);
    }
    else {
        cerrarVentana = true;
    }
}

function cancelKey(evt) {
    if (evt.preventDefault) {
        evt.preventDefault();
        return false;
    }
    else {
        evt.keyCode = 0;
        evt.returnValue = false;
    }
}

function showDown(evt) {
    evt = (evt) ? evt : ((event) ? event : null);
    //alert(event.keyCode);
    if (evt) {
        if (event.keyCode == 13) {
            // When Enter is pressed
            cancelKey(evt);
        }
        if (event.keyCode == 8 && (event.srcElement.type!= "text" && event.srcElement.type!= "textarea" && event.srcElement.type!= "password")) {
            // When backspace is pressed but not in form element
            cancelKey(evt);
        }
        else if (event.keyCode == 116) {
            // When F5 is pressed
            cancelKey(evt);
        }
        else if (event.keyCode == 122) {
            // When F11 is pressed
            cancelKey(evt);
        }
        else if (event.ctrlKey && (event.keyCode == 78 || event.keyCode == 82)) {
            // When ctrl is pressed with R or N
            cancelKey(evt);
        }
        else if (event.ctrlKey && (event.keyCode == 65 || event.keyCode == 85)) {
            // When ctrl is pressed with U or A
            cancelKey(evt);
        }
        else if (event.altKey && (event.keyCode == 37 || event.keyCode == 39)) {
            // stop Alt left or right cursor
            return false;
        }
    }
}

document.onkeydown = showDown;