Here the whole code that you'll need:
Let's consider that your All Regions checkbox field has id- 'AllRegions'
Just put this whole code in your landing page, when you drag an HTML element of your drafted LP:
MktoForms2.whenReady(function (form){
$('#AllRegions').click(function(event){
if($(this).is(":checked")){
$(".mktoFormRow input[type='checkbox']").each(function(index, el) { $(el).prop({"checked": false}); $(el).attr('disabled', true); }); $(this).prop({"checked": true});
}else{
$(".mktoFormRow input[type='checkbox']").each(function(index, el) { $(el).attr('disabled', false); });
}
});
Hope this solves your problem