first commit

common/resources/client/utils/array/group-array-by.ts

@@ -0,0 +1,26 @@
+interface Options<T> {
+  map?: (item: T) => T;
+}
+
+export function groupArrayBy<T>(
+  arr: T[],
+  cb: (item: any) => string,
+  options?: Options<T>,
+): {[key: string]: T[]} {
+  const result: {[key: string]: T[]} = {};
+  for (let i = 0; i < arr.length; i++) {
+    let item = arr[i];
+    const bucketCategory = cb(item);
+    const bucket = result[bucketCategory];
+
+    item = options?.map ? options.map(arr[i]) : arr[i];
+
+    if (!Array.isArray(bucket)) {
+      result[bucketCategory] = [item];
+    } else {
+      result[bucketCategory].push(item);
+    }
+  }
+
+  return result;
+}