From e880a1f60fefeed3fba430dd5c812d34b247a444 Mon Sep 17 00:00:00 2001
From: Julien Deniau <julien.deniau@gmail.com>
Date: Tue, 25 Mar 2025 19:57:28 +0000
Subject: [PATCH 1/2] Call super()" before this in constructors

---
 eslint.config.mjs |  2 --
 src/Map.js        |  2 ++
 src/Operations.js | 10 ++++++++++
 src/Range.js      |  2 ++
 src/Repeat.js     |  2 ++
 5 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/eslint.config.mjs b/eslint.config.mjs
index 1e29c04507..d27ddb9cbd 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -27,13 +27,11 @@ export default tseslint.config(
   {
     rules: {
       eqeqeq: 'error',
-      'constructor-super': 'off',
       'no-constructor-return': 'error',
       'no-else-return': 'error',
       'no-lonely-if': 'error',
       'no-object-constructor': 'error',
       'no-prototype-builtins': 'off',
-      'no-this-before-super': 'off',
       'no-useless-concat': 'error',
       'no-var': 'error',
       'operator-assignment': 'error',
diff --git a/src/Map.js b/src/Map.js
index d0d9d58b61..dd9faf5e49 100644
--- a/src/Map.js
+++ b/src/Map.js
@@ -553,6 +553,8 @@ ValueNode.prototype.iterate = function (fn, reverse) {
 
 class MapIterator extends Iterator {
   constructor(map, type, reverse) {
+    super();
+
     this._type = type;
     this._reverse = reverse;
     this._stack = map._root && mapIteratorFrame(map._root);
diff --git a/src/Operations.js b/src/Operations.js
index 569f3d7793..9c3ba24920 100644
--- a/src/Operations.js
+++ b/src/Operations.js
@@ -44,6 +44,8 @@ import { OrderedMap } from './OrderedMap';
 
 export class ToKeyedSequence extends KeyedSeqImpl {
   constructor(indexed, useKeys) {
+    super();
+
     this._iter = indexed;
     this._useKeys = useKeys;
     this.size = indexed.size;
@@ -89,6 +91,8 @@ ToKeyedSequence.prototype[IS_ORDERED_SYMBOL] = true;
 
 export class ToIndexedSequence extends IndexedSeqImpl {
   constructor(iter) {
+    super();
+
     this._iter = iter;
     this.size = iter.size;
   }
@@ -128,6 +132,8 @@ export class ToIndexedSequence extends IndexedSeqImpl {
 
 export class ToSetSequence extends SetSeqImpl {
   constructor(iter) {
+    super();
+
     this._iter = iter;
     this.size = iter.size;
   }
@@ -153,6 +159,8 @@ export class ToSetSequence extends SetSeqImpl {
 
 export class FromEntriesSequence extends KeyedSeqImpl {
   constructor(entries) {
+    super();
+
     this._iter = entries;
     this.size = entries.size;
   }
@@ -597,6 +605,8 @@ export function skipWhileFactory(collection, predicate, context, useKeys) {
 
 class ConcatSeq extends SeqImpl {
   constructor(iterables) {
+    super();
+
     this._wrappedIterables = iterables.flatMap((iterable) => {
       if (iterable._wrappedIterables) {
         return iterable._wrappedIterables;
diff --git a/src/Range.js b/src/Range.js
index e00a53fb96..dec20b2973 100644
--- a/src/Range.js
+++ b/src/Range.js
@@ -33,6 +33,8 @@ export const Range = (start, end, step = 1) => {
 };
 export class RangeImpl extends IndexedSeqImpl {
   constructor(start, end, step, size) {
+    super();
+
     this._start = start;
     this._end = end;
     this._step = step;
diff --git a/src/Repeat.js b/src/Repeat.js
index bc20177523..c428e213d0 100644
--- a/src/Repeat.js
+++ b/src/Repeat.js
@@ -22,6 +22,8 @@ export const Repeat = (value, times) => {
 
 export class RepeatImpl extends IndexedSeqImpl {
   constructor(value, size) {
+    super();
+
     this._value = value;
     this.size = size;
   }

From 03838f9e8eaf57b680a95fb641b346a1712e876a Mon Sep 17 00:00:00 2001
From: Julien Deniau <julien.deniau@gmail.com>
Date: Tue, 25 Mar 2025 21:59:01 +0000
Subject: [PATCH 2/2] Fix issue with MapIterator re-setting the next method

---
 src/Iterator.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/Iterator.js b/src/Iterator.js
index 1954a3661c..e68aef6eb5 100644
--- a/src/Iterator.js
+++ b/src/Iterator.js
@@ -9,7 +9,10 @@ export const ITERATOR_SYMBOL = REAL_ITERATOR_SYMBOL || FAUX_ITERATOR_SYMBOL;
 
 export class Iterator {
   constructor(next) {
-    this.next = next;
+    if (next) {
+      // Map extends Iterator and has a `next` method, do not erase it in that case. We could have checked `if (next && !this.next)` too.
+      this.next = next;
+    }
   }
 
   toString() {