From b328934b6c5ae8cd723ff719ea7645d381826011 Mon Sep 17 00:00:00 2001
From: Jeremy Nagel <jeremy@gofar.co>
Date: Wed, 27 Nov 2019 14:07:19 +1100
Subject: [PATCH] [BUGFIX] Fix issue with with array constructor

- You can do new Array(4) to generate an array with 4 empty items
- Doing the same with list caused an error
- This broke lodash.deepclone
- This PR restores compatibility with the array constructor

Fixes #1798
---
 lib/list.js       |  5 +++++
 test/list.test.js | 10 ++++++++++
 2 files changed, 15 insertions(+)

diff --git a/lib/list.js b/lib/list.js
index 4c14bd1f..4f4dfed7 100644
--- a/lib/list.js
+++ b/lib/list.js
@@ -27,6 +27,11 @@ function List(items, itemType, parent) {
     }
   }
 
+  if (typeof items === 'number') {
+    // trying to initialise empty array with a length
+    items = [...new Array(items)];
+  }
+
   const arr = [];
   arr.__proto__ = List.prototype;
 
diff --git a/test/list.test.js b/test/list.test.js
index cdc608a3..9a9e834f 100644
--- a/test/list.test.js
+++ b/test/list.test.js
@@ -38,6 +38,16 @@ function PhoneCtor(label, num) {
   this.num = num;
 }
 
+describe('Does not break default Array functionality', function() {
+  it('allows creating an empty length with a specified length', function() {
+    const list = new List(4);
+    list.should.be.an.instanceOf(Array);
+    list.length.should.be.eql(4);
+    should.not.exist(list.itemType);
+    list.toJSON().should.eql([undefined, undefined, undefined, undefined]);
+  });
+});
+
 describe('list of items typed by a class', function() {
   it('allows itemType to be a class', function() {
     const phones = givenPhones();