needs filterMap

tgui/packages/common/collections.ts

@@ -123,6 +123,26 @@ export const map = iterateeFn => collection => {
   throw new Error(`map() can't iterate on type ${typeof collection}`);
 };
 
+/**
+ * Given a collection, will run each element through an iteratee function.
+ * Will then filter out undefined values.
+ */
+export const filterMap = <T, U>(
+  collection: T[],
+  iterateeFn: (value: T) => U | undefined
+): U[] => {
+  const finalCollection: U[] = [];
+
+  for (const value of collection) {
+    const output = iterateeFn(value);
+    if (output !== undefined) {
+      finalCollection.push(output);
+    }
+  }
+
+  return finalCollection;
+};
+
 const COMPARATOR = (objA, objB) => {
   const criteriaA = objA.criteria;
   const criteriaB = objB.criteria;