@RemoteAction
    public static void putAccount(Account a){
        update a;
    }

function Account(){
    this.Id = null;
}
function putAccount(){
    var acct = new Account();
    acct.Id = document.getElementById("accountPutId").value;
    acct.NumberOfEmployees = parseInt(document.getElementById("accountPutNumEmp").value);
    console.log(acct);
    AccountRemote.putAccount(acct, function(result, event){
        console.log(event);
    });
    document.getElementById("accountPutId").value = "";
    document.getElementById("accountPutName").value = "";
}

Account {Id: "001o000000BbbzbAAB", NumberOfEmployees: 1}