From 3446557eae0dd6096ca388872a0ad28b7e2d4202 Mon Sep 17 00:00:00 2001
From: Josh Abernathy <joshaber@gmail.com>
Date: Wed, 27 Jul 2016 16:40:43 -0400
Subject: [PATCH] Add find and findIndex to ReadonlyArray

---
 src/lib/es2015.core.d.ts | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/lib/es2015.core.d.ts b/src/lib/es2015.core.d.ts
index 206b8b8f9bf..dcfe9a0b92e 100644
--- a/src/lib/es2015.core.d.ts
+++ b/src/lib/es2015.core.d.ts
@@ -343,6 +343,30 @@ interface ObjectConstructor {
     defineProperty(o: any, propertyKey: PropertyKey, attributes: PropertyDescriptor): any;
 }
 
+interface ReadonlyArray<T> {
+  /**
+    * Returns the value of the first element in the array where predicate is true, and undefined
+    * otherwise.
+    * @param predicate find calls predicate once for each element of the array, in ascending
+    * order, until it finds one where predicate returns true. If such an element is found, find
+    * immediately returns that element value. Otherwise, find returns undefined.
+    * @param thisArg If provided, it will be used as the this value for each invocation of
+    * predicate. If it is not provided, undefined is used instead.
+    */
+  find(predicate: (value: T, index: number, obj: Array<T>) => boolean, thisArg?: any): T | undefined;
+
+  /**
+    * Returns the index of the first element in the array where predicate is true, and undefined
+    * otherwise.
+    * @param predicate find calls predicate once for each element of the array, in ascending
+    * order, until it finds one where predicate returns true. If such an element is found, 
+    * findIndex immediately returns that element index. Otherwise, findIndex returns -1.
+    * @param thisArg If provided, it will be used as the this value for each invocation of
+    * predicate. If it is not provided, undefined is used instead.
+    */
+  findIndex(predicate: (value: T) => boolean, thisArg?: any): number;
+}
+
 interface RegExp {
     /**
       * Returns a string indicating the flags of the regular expression in question. This field is read-only.