How can I serializeArray for unchecked checkboxes?

It's probably easiest to just do it yourself:

 var serialized = $('input:checkbox').map(function() {
   return { name: this.name, value: this.checked ? this.value : "false" };
 });

If there are other inputs, then you could serialize the form, and then find the unchecked checkboxes with something like the above and append that result to the first array.

you can use this get unchecked values

$.fn.serializeObject = function () {
var o = {};
var a = this.serializeArray();
$.each(a, function () {
    if (o[this.name] !== undefined) {
        if (!o[this.name].push) {
            o[this.name] = [o[this.name]];
        }
        o[this.name].push(this.value || '');
    } else {
        o[this.name] = this.value || '';
    }
});
var $radio = $('input[type=radio],input[type=checkbox]',this);
$.each($radio,function(){
    if(!o.hasOwnProperty(this.name)){
        o[this.name] = '';
    }
});
return o;
};

code samples

serializeArray ignores the checkboxes which are not checked. You can try something like this.

Working demo

    var serializedObj = {};
    $("form input:checkbox").each(function(){
        serializedObj[this.name] = this.checked;
    });