add exclude_tags filter

_config/filters.js

@@ -34,6 +34,37 @@ module.exports = function (eleventyConfig, { TIME_ZONE, defaultLanguage }) {
         return filtered;
     });
 
+    // takes a collection or all collections and returns only the tags no matched
+    // works with arrays and key-objects so may repurpose under different name
+    eleventyConfig.addFilter("exclude_tags", function (collection, ...tagsToExclude) {
+        if (!collection || typeof collection !== "object") {
+            console.warn("[exclude_tags] Invalid collection input:", collection);
+            return collection;
+        }
+
+        // handle both array and key-value object inputs
+        const items = Array.isArray(collection) ? collection : Object.values(collection);
+
+        // filter out items where any of the tagsToExclude are in item.data.tags
+        const filtered = items.filter(item => {
+            const itemTags = item.data && item.data.tags ? item.data.tags : [];
+            return !tagsToExclude.some(tag => itemTags.includes(tag));
+        });
+
+        // if input was a key-value object, reconstruct it
+        if (!Array.isArray(collection)) {
+            const result = {};
+            Object.keys(collection).forEach(key => {
+                if (filtered.includes(collection[key])) {
+                    result[key] = collection[key];
+                }
+            });
+            return result;
+        }
+
+        return filtered;
+    });
+
     const LOCALE_URL_DEBUG = process.env.LOCALE_URL_DEBUG === "1" || process.env.LOCALE_URL_DEBUG === "true";
 
     // locale_url replacement that uses pre-compile filesystem