Dtri,
<head lang="en">
<meta charset="UTF-8">
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<title></title>
</head>
<body>
<form action="json.txt">
<input type="text" name="bublik" value="1">
<input type="text" name="bublik2" value="2">
<input type="text" name="bublik" value="3">
</form>
<button type="submit" class="a_submit">Submit</button>
<div class="wrapper"></div>
<script>
$('.a_submit').on('click', function (form) {
form.preventDefault();
var arr = $(this).prev('form').serializeArray(), obj = {};
$.each(arr, function(indx, el){
obj[el.name] ? obj[el.name].push(el.value) : (obj[el.name] = [el.value]);
});
$('.wrapper').html(JSON.stringify(obj));
});
</script>
</body>