How to make key value pair array when chekbox checked using jquery?

I have multiple checkbox, when i check a checkbox two key value pair will generate.
Like this : Object {id: "101", name: "example"}

This will generate for every checkbox checked and i want for multiple checkbox checked array. look like this :

[{id:"id1",name:"name1"},{id:"id2",name:"name2"}]

What I have done

$('.chkCompare').click(function(event) {
        var value = [];
        var projectName = {};
        var span = $(this).attr('id');
        value = $('.chkCompare:checked').map(function() {
            $('#span' + span).text('ADDED').css({
                "color": "green"
            });
            projectName['id'] = $(this).attr('id');
            projectName['name'] = $(this).attr('title');
            return value.push(projectName);
        }).get();

When i uncheck checkbox they will be remove from array and want to prevent check maximum 3 checkbox if >3 then show an alert box.