From 9d4781c0f4e760afd8f88d53d01df66bbeb46462 Mon Sep 17 00:00:00 2001
From: Perryvw <perry.wesel@gmail.com>
Date: Thu, 3 Oct 2019 21:15:02 +0200
Subject: [PATCH 1/2] Added support for array.find

---
 src/LuaLib.ts                    |  1 +
 src/LuaTransformer.ts            |  2 ++
 src/lualib/ArrayFind.ts          | 14 ++++++++++++++
 test/unit/builtins/array.spec.ts | 16 ++++++++++++++++
 4 files changed, 33 insertions(+)
 create mode 100644 src/lualib/ArrayFind.ts

diff --git a/src/LuaLib.ts b/src/LuaLib.ts
index 050e1eaf3..9d15f9fb4 100644
--- a/src/LuaLib.ts
+++ b/src/LuaLib.ts
@@ -6,6 +6,7 @@ export enum LuaLibFeature {
     ArrayEvery = "ArrayEvery",
     ArrayFilter = "ArrayFilter",
     ArrayForEach = "ArrayForEach",
+    ArrayFind = "ArrayFind",
     ArrayFindIndex = "ArrayFindIndex",
     ArrayIndexOf = "ArrayIndexOf",
     ArrayMap = "ArrayMap",
diff --git a/src/LuaTransformer.ts b/src/LuaTransformer.ts
index fcb8c4cd0..cff5f45df 100644
--- a/src/LuaTransformer.ts
+++ b/src/LuaTransformer.ts
@@ -5113,6 +5113,8 @@ export class LuaTransformer {
                 );
             case "forEach":
                 return this.transformLuaLibFunction(LuaLibFeature.ArrayForEach, node, caller, ...params);
+            case "find":
+                return this.transformLuaLibFunction(LuaLibFeature.ArrayFind, node, caller, ...params);
             case "findIndex":
                 return this.transformLuaLibFunction(LuaLibFeature.ArrayFindIndex, node, caller, ...params);
             case "indexOf":
diff --git a/src/lualib/ArrayFind.ts b/src/lualib/ArrayFind.ts
new file mode 100644
index 000000000..66970122a
--- /dev/null
+++ b/src/lualib/ArrayFind.ts
@@ -0,0 +1,14 @@
+// https://www.ecma-international.org/ecma-262/10.0/index.html#sec-array.prototype.find
+function __TS__ArrayFind<T>(this: void, arr: T[], callbackFn: (element: T, index?: number, array?: T[]) => boolean): T {
+    const len = arr.length;
+    let k = 0;
+    while (k < len) {
+        const elem = arr[k];
+        if (callbackFn(elem, k, arr)) {
+            return elem;
+        }
+        k = k + 1;
+    }
+
+    return undefined;
+}
diff --git a/test/unit/builtins/array.spec.ts b/test/unit/builtins/array.spec.ts
index edac44090..3171eb805 100644
--- a/test/unit/builtins/array.spec.ts
+++ b/test/unit/builtins/array.spec.ts
@@ -246,9 +246,25 @@ test("array.forEach (%p)", () => {
     `.expectToMatchJsResult();
 });
 
+test.each([
+    { array: [], predicate: "elem > 3" },
+    { array: [0, 2, 4, 8], predicate: "elem > 10" },
+    { array: [0, 2, 4, 8], predicate: "elem > 7" },
+    { array: [0, 2, 4, 8], predicate: "elem == 0" },
+    { array: [0, 2, 4, 8], predicate: "elem > 7" },
+    { array: [0, 2, 4, 8], predicate: "true" },
+    { array: [0, 2, 4, 8], predicate: "false" },
+])("array.find (%p)", ({ array, predicate }) => {
+    util.testFunction`
+        const array = ${util.valueToString(array)};
+        return array.find((elem, index, arr) => ${predicate} && arr[index] === elem);
+    `.expectToMatchJsResult();
+});
+
 test.each([
     { array: [], searchElement: 3 },
     { array: [0, 2, 4, 8], searchElement: 10 },
+    { array: [0, 2, 4, 8], searchElement: 0 },
     { array: [0, 2, 4, 8], searchElement: 8 },
 ])("array.findIndex (%p)", ({ array, searchElement }) => {
     util.testFunction`

From 1fa4a1e0be3526241bd2ca60aa7f56e774dfa667 Mon Sep 17 00:00:00 2001
From: Perryvw <perry.wesel@gmail.com>
Date: Sat, 5 Oct 2019 15:49:12 +0200
Subject: [PATCH 2/2] Changed lualib function signature to match TS lib

---
 src/lualib/ArrayFind.ts | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/lualib/ArrayFind.ts b/src/lualib/ArrayFind.ts
index 66970122a..370200df1 100644
--- a/src/lualib/ArrayFind.ts
+++ b/src/lualib/ArrayFind.ts
@@ -1,10 +1,14 @@
 // https://www.ecma-international.org/ecma-262/10.0/index.html#sec-array.prototype.find
-function __TS__ArrayFind<T>(this: void, arr: T[], callbackFn: (element: T, index?: number, array?: T[]) => boolean): T {
+function __TS__ArrayFind<T>(
+    this: void,
+    arr: T[],
+    predicate: (value: T, index: number, obj: T[]) => unknown
+): T | undefined {
     const len = arr.length;
     let k = 0;
     while (k < len) {
         const elem = arr[k];
-        if (callbackFn(elem, k, arr)) {
+        if (predicate(elem, k, arr)) {
             return elem;
         }
         k = k + 1;