jQuery get values of checked checkboxes into array

Call .get() at the very end to turn the resulting jQuery object into a true array.

$("#merge_button").click(function(event){
    event.preventDefault();
    var searchIDs = $("#find-table input:checkbox:checked").map(function(){
      return $(this).val();
    }).get(); // <----
    console.log(searchIDs);
});

Per the documentation:

As the return value is a jQuery object, which contains an array, it’s very common to call .get() on the result to work with a basic array.