The event.preventDefault is not working - php

Question

I have this codes below and I can't get the event.preventDefault() working. The thing is, I already have other form and it worked well.
I'm sure you guys can help me out.
Here are the codes:
$(document).on('dblclick','td.selecionaCodigoCliente', function(){
//event.preventDefault();
$("#mostraClienteSelecionado").html("Cliente [" + this.parentNode.children[0].innerText + "]: " + this.parentNode.children[1].innerText);
$('input[name="salvaCodigoCliente"]').attr('value',this.parentNode.children[0].innerText);
});
PS: this code above is for the dblclick in a table.
$("#botaoSalvaOS").on('submit',function(event){
$.post("salvaOS.php", $(this).serialize(),function(){
$("#sucessoOS").html("Dados inseridos com sucesso");
});
event.preventDefault();
})
PS: this cobe is for handle the submit
When I submit the form, I get the PHP response. This is the PHP code.
<?php
include_once('db.php');
$dataAberturaOS = date('d-m-Y');
$codigoCliente = $_POST['salvaCodigoCliente'];
$equipamento = $_POST['equipamento'];
$marca = $_POST['marca'];
$modelo = $_POST['modelo'];
$nserie = $_POST['nserie'];
$acessorio = $_POST['acessorio'];
$observacao = $_POST['observacao'];
$defeitos = $_POST['defeitos'];
if(mysql_query("INSERT INTO ordemdeservico VALUES('NULL', '$equipamento', '$marca', '$modelo', '$nserie', '$observacao', '$acessorio', '$defeitos', '$codigoCliente', '$dataAberturaOS', '$dataAberturaOS', 'ABERTA')"))
echo "Successfully Inserted";
else
echo "Insertion Failed";
?>
Thanks in advance.

Answer 1

Your code seems correct. Maybe Abhik Chakraborty comment may help. You can also try to add a event.stopPropagation(); to avoid event bubbling up to a different handler.

Answer 2

Try returning false instead:
$("#botaoSalvaOS").on('submit',function(event){
$.post("salvaOS.php", $(this).serialize(),function(){
$("#sucessoOS").html("Dados inseridos com sucesso");
});
return false;
})