Refactor array utility

Author: skovhus

server/src/util/array.ts

@@ -15,17 +15,24 @@ export function uniq<A>(a: A[]): A[] {
 
 /**
  * Removed all duplicates from the list based on the hash function.
+ * First element matching the hash function wins.
  */
-export function uniqueBasedOnHash<A>(list: A[], elementToHash: (a: A) => string): A[] {
-  const hashSet = new Set()
+export function uniqueBasedOnHash<A extends Record<string, any>>(
+  list: A[],
+  elementToHash: (a: A) => string,
+  __result: A[] = [],
+): A[] {
+  const result: typeof list = []
+  const hashSet = new Set<string>()
 
-  return list.reduce((accumulator, currentValue) => {
-    const hash = elementToHash(currentValue)
+  list.forEach(element => {
+    const hash = elementToHash(element)
     if (hashSet.has(hash)) {
-      return accumulator
+      return
     }
     hashSet.add(hash)
+    result.push(element)
+  })
 
-    return [...accumulator, currentValue]
-  }, [])
+  return result
 }