Index: node_modules/es-toolkit/dist/array/differenceBy.mjs
===================================================================
--- node_modules/es-toolkit/dist/array/differenceBy.mjs	(revision a762898ecd37a452c782821d4c2c4955c6ed2521)
+++ node_modules/es-toolkit/dist/array/differenceBy.mjs	(revision a762898ecd37a452c782821d4c2c4955c6ed2521)
@@ -0,0 +1,8 @@
+function differenceBy(firstArr, secondArr, mapper) {
+    const mappedSecondSet = new Set(secondArr.map(item => mapper(item)));
+    return firstArr.filter(item => {
+        return !mappedSecondSet.has(mapper(item));
+    });
+}
+
+export { differenceBy };