From f5a6804e2b433483e3304e2c3db4f7023d6428e1 Mon Sep 17 00:00:00 2001
From: Denis Sikuler <progwork@yandex.com>
Date: Fri, 24 Mar 2017 00:00:56 +0300
Subject: [PATCH] Make replaceAt faster

---
 src/timm.js | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/timm.js b/src/timm.js
index d25923d..a4b2294 100755
--- a/src/timm.js
+++ b/src/timm.js
@@ -227,10 +227,14 @@ export function removeAt<T>(array: Array<T>, idx: number): Array<T> {
 // -- ```
 export function replaceAt<T>(array: Array<T>, idx: number, newItem: T): Array<T> {
   if (array[idx] === newItem) return array;
-  return array
-    .slice(0, idx)
-    .concat([newItem])
-    .concat(array.slice(idx + 1));
+
+  const len: number = array.length;
+  const result: Array<T> = Array(len);
+  for (let i = 0; i < len; i++) {
+    result[i] = array[i];
+  }
+  result[idx] = newItem;
+  return result;
 }
 
 // ===============================================