Deferreds can make your work simpler.
var deferreds = $('.checked-box').map(function(i, elem) {
return $.ajax(params);
});
$.when.apply(null, deferreds.get()).then(function() { ... });
Hope this should work.
The concept is
$.when(
$.ajax( "1" ),
$.ajax( "2" ),
$.ajax( "3" )
).then( successFunc, failureFunc );
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…