A filter uses a JQuery selector (attribute, class, or id) to reduce by category. A sortBy uses the JQuery selector to get a value for comparison.
The "opt-kind" directive specifies a "filter" or "sortBy" key for an element group. For each element in that group, "ok-sel" specifies the selector, and makes that element clickable to invoke the sort or filter.
Selector-Based Filter
Selector and Value-Based Sort
The "opt-kind" directive is either "sortBy" or "filter", which corresponds to the same-named Isotope configuration keys.
The element becomes clickable and emits a message to the isotope-container when clicked.
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Each element uses the "ok-sel" attribute for indicating a JQuery selector, and additionally for "sortBy, an "ok-type" attribute (e.g. Integer) to indicate the type-casting for the element's string value in the sort's comparisons.
Removing an element
Deleting an item from the Angular array automatically removes it from the Isotope container.
Note that the "extra" item is added to the Isotope container directly and cannot be removed this way.