function ajax() {
};
ajax.prototype.iniciar = function() {

    try{
        this.xmlhttp = new XMLHttpRequest();
    }catch(ee){
        try{
            this.xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
        }catch(e){
            try{
                this.xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
            }catch(E){
                this.xmlhttp = false;
            }
        }
    }
    return true;
}

ajax.prototype.ocupado = function() {
    estadoAtual = this.xmlhttp.readyState;
    return (estadoAtual && (estadoAtual < 4));
}

ajax.prototype.processa = function() {
    if (this.xmlhttp.readyState == 4 && this.xmlhttp.status == 200) {
        return true;
    }
}

ajax.prototype.enviar = function(url, metodo, modo) {
    if (!this.xmlhttp) {
        this.iniciar();
    }
    if (!this.ocupado()) {
        if(metodo == "GET") {
            this.xmlhttp.open("GET", url, modo);
            this.xmlhttp.send(null);
        } else {        
            this.xmlhttp.open("POST", url, modo);
            this.xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");
            this.xmlhttp.setRequestHeader("Cache-Control", "no-store, no-cache, must-revalidate");
            this.xmlhttp.setRequestHeader("Cache-Control", "post-check=0, pre-check=0");
            this.xmlhttp.setRequestHeader("Pragma", "no-cache");
            this.xmlhttp.send(url);
        }    

        if (this.processa) {
            return unescape(this.xmlhttp.responseText.replace(/\+/g," "));
        }
    }
    return false;
}
function Limpar(valor, validos) {
    // retira caracteres invalidos da string
    var result = "";
    var aux;
    for (var i=0; i < valor.length; i++) {
        aux = validos.indexOf(valor.substring(i, i+1));
        if (aux>=0) {
            result += aux;
        }
    }
    return result;
}

//Formata número tipo moeda usando o evento onKeyDown

function Formata(campo,tammax,teclapres,decimal) {
    var tecla = teclapres.keyCode;
    vr = Limpar(campo.value,"0123456789");
    tam = vr.length;
    dec=decimal

    if (tam < tammax && tecla != 8){ tam = vr.length + 1 ; }

    if (tecla == 8 )
    { tam = tam - 1 ; }

    if ( tecla == 8 || tecla >= 48 && tecla <= 57 || tecla >= 96 && tecla <= 105 )
    {

    if ( tam <= dec )
    { campo.value = vr ; }

    if ( (tam > dec) && (tam <= 5) ){
    campo.value = vr.substr( 0, tam - 2 ) + "," + vr.substr( tam - dec, tam ) ; }
    if ( (tam >= 6) && (tam <= 8) ){
        campo.value = vr.substr( 0, tam - 5 ) + "." + vr.substr( tam - 5, 3 ) + "," + vr.substr( tam - dec, tam ) ; 
    }
    if ( (tam >= 9) && (tam <= 11) ){
        campo.value = vr.substr( 0, tam - 8 ) + "." + vr.substr( tam - 8, 3 ) + "." + vr.substr( tam - 5, 3 ) + "," + vr.substr( tam - dec, tam ) ; }
    if ( (tam >= 12) && (tam <= 14) ){
        campo.value = vr.substr( 0, tam - 11 ) + "." + vr.substr( tam - 11, 3 ) + "." + vr.substr( tam - 8, 3 ) + "." + vr.substr( tam - 5, 3 ) + "," + vr.substr( tam - dec, tam ) ; }
    if ( (tam >= 15) && (tam <= 17) ){
    campo.value = vr.substr( 0, tam - 14 ) + "." + vr.substr( tam - 14, 3 ) + "." + vr.substr( tam - 11, 3 ) + "." + vr.substr( tam - 8, 3 ) + "." + vr.substr( tam - 5, 3 ) + "," + vr.substr( tam - 2, tam ) ;}
} 

}