From 0aed66f6ef5d026e01980957f5a27fb5dc98b041 Mon Sep 17 00:00:00 2001
From: Angus MacDonald <amacdonald@google.com>
Date: Fri, 27 Nov 2020 11:51:12 -0600
Subject: [PATCH] Add arrayf.filterUntilFalse

---
 src/arrayf/arrayf.ts | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/arrayf/arrayf.ts b/src/arrayf/arrayf.ts
index c53ee4696a..0b9d188044 100644
--- a/src/arrayf/arrayf.ts
+++ b/src/arrayf/arrayf.ts
@@ -28,5 +28,21 @@ export class arrayf {
         return output;
     }
 
-
-}
\ No newline at end of file
+    /**
+     * Return every value before the first occurrence of a value that evaluates
+     * to false when passed to the conditionFn.
+     * ```
+     * // Returns [1, 3, 7]
+     * arrayf.filterUntilFalse([1,3,7,40,2,6], (x) => x < 10);
+     * ```
+     */
+    static filterUntilFalse<T>(
+        values: T[], conditionFn: (value: T, index: number) => boolean
+    ): T[] {
+        let index: number = 0;
+        while (index < values.length && conditionFn(values[index], index)) {
+            index++;
+        }
+        return values.slice(0, index);
+    }
+}