From 7c40b4df578da1a30f6726fce90f546f55300974 Mon Sep 17 00:00:00 2001
From: Nick Colley <nick.colley@digital.cabinet-office.gov.uk>
Date: Mon, 24 Feb 2020 16:31:42 +0000
Subject: [PATCH] Add Element.prototype.previousElementSibling polyfill

---
 .../previousElementSibling/config.toml        | 25 +++++++++++
 .../previousElementSibling/detect.js          |  1 +
 .../previousElementSibling/polyfill.js        |  7 +++
 .../prototype/previousElementSibling/tests.js | 45 +++++++++++++++++++
 4 files changed, 78 insertions(+)
 create mode 100644 polyfills/Element/prototype/previousElementSibling/config.toml
 create mode 100644 polyfills/Element/prototype/previousElementSibling/detect.js
 create mode 100644 polyfills/Element/prototype/previousElementSibling/polyfill.js
 create mode 100644 polyfills/Element/prototype/previousElementSibling/tests.js

diff --git a/polyfills/Element/prototype/previousElementSibling/config.toml b/polyfills/Element/prototype/previousElementSibling/config.toml
new file mode 100644
index 000000000..123e9e31b
--- /dev/null
+++ b/polyfills/Element/prototype/previousElementSibling/config.toml
@@ -0,0 +1,25 @@
+aliases = [ ]
+dependencies = [
+  "Element",
+  "Object.defineProperty"
+]
+license = "MIT"
+docs = "https://developer.mozilla.org/en-US/docs/Web/API/NonDocumentTypeChildNode/previousElementSibling"
+
+[browsers]
+android = "todo"
+bb = "todo"
+chrome = "todo"
+edge = "todo"
+edge_mob = "todo"
+firefox = "todo"
+ios_chr = "todo"
+ios_saf = "todo"
+ie = "todo"
+ie_mob = "todo"
+opera = "todo"
+op_mini = "todo"
+op_mob = "todo"
+safari = "todo"
+firefox_mob = "todo"
+samsung_mob = "todo"
diff --git a/polyfills/Element/prototype/previousElementSibling/detect.js b/polyfills/Element/prototype/previousElementSibling/detect.js
new file mode 100644
index 000000000..a0cc375c4
--- /dev/null
+++ b/polyfills/Element/prototype/previousElementSibling/detect.js
@@ -0,0 +1 @@
+'document' in self && "previousElementSibling" in document.documentElement
diff --git a/polyfills/Element/prototype/previousElementSibling/polyfill.js b/polyfills/Element/prototype/previousElementSibling/polyfill.js
new file mode 100644
index 000000000..efd20a14f
--- /dev/null
+++ b/polyfills/Element/prototype/previousElementSibling/polyfill.js
@@ -0,0 +1,7 @@
+Object.defineProperty(Element.prototype, 'previousElementSibling', {
+	get: function(){
+		var el = this.previousSibling;
+		while (el && el.nodeType !== 1) { el = el.previousSibling; }
+		return el;
+	}
+});
diff --git a/polyfills/Element/prototype/previousElementSibling/tests.js b/polyfills/Element/prototype/previousElementSibling/tests.js
new file mode 100644
index 000000000..cb8eff7d3
--- /dev/null
+++ b/polyfills/Element/prototype/previousElementSibling/tests.js
@@ -0,0 +1,45 @@
+it("should return null if the node is the only child of its parent node", function () {
+  var parent = document.createElement('div'),
+      p = document.createElement('p');
+  parent.appendChild(p);
+
+  proclaim.strictEqual(p.nextElementSibling, null);
+});
+
+it("should return null if the node only has text sibling", function () {
+  var parent = document.createElement('div'),
+      p = document.createElement('p');
+      text = document.createTextNode('Hi there, how are you doing today?');
+  parent.appendChild(p);
+  parent.appendChild(text);
+
+  proclaim.strictEqual(p.nextElementSibling, null);
+});
+
+it("should return null if the node only has comment sibling", function () {
+  var parent = document.createElement('div'),
+      p = document.createElement('p');
+      comment = document.createComment('This is a comment in the document.');
+  parent.appendChild(p);
+  parent.appendChild(comment);
+
+  proclaim.strictEqual(p.nextElementSibling, null);
+});
+
+it("should return the first child element", function () {
+  var parent = document.createElement('div'),
+      h2 = document.createElement('h2'),
+      p1 = document.createElement('p'),
+      p2 = document.createElement('p'),
+      p3 = document.createElement('p'),
+      text = document.createTextNode('Hi there, how are you doing today?'),
+      comment = document.createComment('This is a comment in the document.');
+  parent.appendChild(h2);
+  parent.appendChild(text);
+  parent.appendChild(comment);
+  parent.appendChild(p1);
+  parent.appendChild(p2);
+  parent.appendChild(p3);
+
+  proclaim.strictEqual(h2.nextElementSibling, p1);
+});