From 57d239c128ac0ad9be5390c6f1a23e9ab8a14dc7 Mon Sep 17 00:00:00 2001
From: Guangcong Luo <guangcongluo@gmail.com>
Date: Thu, 23 Jul 2020 13:19:12 -0700
Subject: [PATCH] Use <script nomodule> for polyfills (#1549)

This should make PS marginally slower on really old browsers,
marginally faster on modern browsers, neither of which should be
remotely noticeable.

The intended actual impact is to make it easier to maintain
(`battle-dex` is clearly the wrong place for polyfills) and easier
to reuse outside of PS.
---
 index.template.html         |   1 +
 js/lib/ps-polyfill.js       | 117 ++++++++++++++++++++++++++++++++++++
 js/replay-embed.template.js |   1 +
 preactalpha.template.html   |   1 +
 src/battle-dex.ts           |  84 --------------------------
 testclient-beta.html        |   1 +
 testclient.html             |   1 +
 7 files changed, 122 insertions(+), 84 deletions(-)
 create mode 100644 js/lib/ps-polyfill.js

diff --git a/index.template.html b/index.template.html
index 8e28e788a7..086688fbcd 100644
--- a/index.template.html
+++ b/index.template.html
@@ -98,6 +98,7 @@ <h3><button class="closebutton" tabindex="-1"><i class="fa fa-times-circle"></i>
 	var LM = document.getElementById('loading-message');
 	LM.innerHTML += ' DONE<br />Loading libraries...';
 </script>
+<script nomodule src="//play.pokemonshowdown.com/js/lib/ps-polyfill.js"></script>
 <script src="//play.pokemonshowdown.com/config/config.js?"></script>
 <script src="//play.pokemonshowdown.com/js/lib/jquery-2.1.4.min.js"></script>
 <script src="//play.pokemonshowdown.com/js/lib/jquery-cookie.js"></script>
diff --git a/js/lib/ps-polyfill.js b/js/lib/ps-polyfill.js
new file mode 100644
index 0000000000..50a6bc6720
--- /dev/null
+++ b/js/lib/ps-polyfill.js
@@ -0,0 +1,117 @@
+/**
+ * PS polyfill
+ *
+ * PS uses its own polyfills optimized for performance rather than
+ * standards-compliance (we simply don't use the features these
+ * polyfills don't provide).
+ *
+ * The biggest relevant difference is that we don't use
+ * `Object.defineProperty`, so you can't use `for...in` on Arrays,
+ * which everyone tells you not to do, anyway - you should be using
+ * `for...i` loops (or `for...of` with Babel's `assumeArray` setting).
+ *
+ * This polyfill is intended to be used in <script nomodule>. All
+ * polyfills here already exist in all browsers supporting nomodule.
+ *
+ * For convenience, I've marked all these with the ES spec they were
+ * introduced in (note that ES2015 is ES6 here).
+ *
+ * @license MIT
+ * @author Guangcong Luo <guangcongluo@gmail.com>
+ */
+
+// ES5
+if (!Array.prototype.indexOf) {
+	Array.prototype.indexOf = function indexOf(searchElement, fromIndex) {
+		for (var i = (fromIndex || 0); i < this.length; i++) {
+			if (this[i] === searchElement) return i;
+		}
+		return -1;
+	};
+}
+// ES2016, predates nomodule
+if (!Array.prototype.includes) {
+	Array.prototype.includes = function includes(thing) {
+		return this.indexOf(thing) !== -1;
+	};
+}
+// ES5
+if (!Array.isArray) {
+	Array.isArray = function isArray(thing) {
+		return Object.prototype.toString.call(thing) === '[object Array]';
+	};
+}
+// ES6
+if (!String.prototype.includes) {
+	String.prototype.includes = function includes(thing) {
+		return this.indexOf(thing) !== -1;
+	};
+}
+// ES6
+if (!String.prototype.startsWith) {
+	String.prototype.startsWith = function startsWith(thing) {
+		return this.slice(0, thing.length) === thing;
+	};
+}
+// ES6
+if (!String.prototype.endsWith) {
+	String.prototype.endsWith = function endsWith(thing) {
+		return this.slice(-thing.length) === thing;
+	};
+}
+// ES5
+if (!String.prototype.trim) {
+	String.prototype.trim = function trim() {
+		return this.replace(/^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g, '');
+	};
+}
+// ES6
+if (!Object.assign) {
+	Object.assign = function assign(thing, rest) {
+		for (var i = 1; i < arguments.length; i++) {
+			var source = arguments[i];
+			for (var k in source) {
+				thing[k] = source[k];
+			}
+		}
+		return thing;
+	};
+}
+// ES2017, predates nomodule
+if (!Object.values) {
+	Object.values = function values(thing) {
+		var out = [];
+		for (var k in thing) {
+			out.push(thing[k]);
+		}
+		return out;
+	};
+}
+// ES5
+if (!Object.keys) {
+	Object.keys = function keys(thing) {
+		var out = [];
+		for (var k in thing) {
+			out.push(k);
+		}
+		return out;
+	};
+}
+// ES2017, predates nomodule
+if (!Object.entries) {
+	Object.entries = function entries(thing) {
+		var out = [];
+		for (var k in thing) {
+			out.push([k, thing[k]]);
+		}
+		return out;
+	};
+}
+// ES5
+if (!Object.create) {
+	Object.create = function (proto) {
+		function F() {}
+		F.prototype = proto;
+		return new F();
+	};
+}
diff --git a/js/replay-embed.template.js b/js/replay-embed.template.js
index 699bb088f5..5783d14570 100644
--- a/js/replay-embed.template.js
+++ b/js/replay-embed.template.js
@@ -17,6 +17,7 @@ linkStyle('https://play.pokemonshowdown.com/style/battle.css?a7');
 linkStyle('https://play.pokemonshowdown.com/style/replay.css?a7');
 linkStyle('https://play.pokemonshowdown.com/style/utilichart.css?a7');
 
+requireScript('https://play.pokemonshowdown.com/js/lib/ps-polyfill.js');
 requireScript('https://play.pokemonshowdown.com/config/config.js?a7');
 requireScript('https://play.pokemonshowdown.com/js/lib/jquery-1.11.0.min.js');
 requireScript('https://play.pokemonshowdown.com/js/lib/lodash.compat.js');
diff --git a/preactalpha.template.html b/preactalpha.template.html
index d42a93607f..b279cde22b 100644
--- a/preactalpha.template.html
+++ b/preactalpha.template.html
@@ -53,6 +53,7 @@ <h3><button class="closebutton" tabindex="-1" aria-label="Close"><i class="fa fa
 	</script>
 	<script defer src="/config/config.js?"></script>
 	<script defer src="/js/client-core.js?"></script>
+	<script nomodule defer src="/js/lib/ps-polyfill.js"></script>
 
 	<script defer src="/js/battle-dex.js?"></script>
 	<script defer src="/js/battle-text-parser.js?"></script>
diff --git a/src/battle-dex.ts b/src/battle-dex.ts
index c63bff4ff6..393a7693f8 100644
--- a/src/battle-dex.ts
+++ b/src/battle-dex.ts
@@ -21,90 +21,6 @@
 declare var require: any;
 declare var global: any;
 
-if (!Array.prototype.indexOf) {
-	Array.prototype.indexOf = function indexOf(searchElement, fromIndex) {
-		for (let i = (fromIndex || 0); i < this.length; i++) {
-			if (this[i] === searchElement) return i;
-		}
-		return -1;
-	};
-}
-if (!Array.prototype.includes) {
-	Array.prototype.includes = function includes(thing) {
-		return this.indexOf(thing) !== -1;
-	};
-}
-if (!Array.isArray) {
-	Array.isArray = function isArray(thing): thing is any[] {
-		return Object.prototype.toString.call(thing) === '[object Array]';
-	};
-}
-if (!String.prototype.includes) {
-	String.prototype.includes = function includes(thing) {
-		return this.indexOf(thing) !== -1;
-	};
-}
-if (!String.prototype.startsWith) {
-	String.prototype.startsWith = function startsWith(thing) {
-		return this.slice(0, thing.length) === thing;
-	};
-}
-if (!String.prototype.endsWith) {
-	String.prototype.endsWith = function endsWith(thing) {
-		return this.slice(-thing.length) === thing;
-	};
-}
-if (!String.prototype.trim) {
-	String.prototype.trim = function trim() {
-		return this.replace(/^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g, '');
-	};
-}
-if (!Object.assign) {
-	Object.assign = function assign(thing: any, rest: any) {
-		for (let i = 1; i < arguments.length; i++) {
-			let source = arguments[i];
-			for (let k in source) {
-				thing[k] = source[k];
-			}
-		}
-		return thing;
-	};
-}
-if (!Object.values) {
-	Object.values = function values(thing: any) {
-		let out: any[] = [];
-		for (let k in thing) {
-			out.push(thing[k]);
-		}
-		return out;
-	};
-}
-if (!Object.keys) {
-	Object.keys = function keys(thing: any) {
-		let out: any[] = [];
-		for (let k in thing) {
-			out.push(k);
-		}
-		return out;
-	};
-}
-if (!Object.entries) {
-	Object.entries = function entries(thing: any) {
-		let out: any[] = [];
-		for (let k in thing) {
-			out.push([k, thing[k]]);
-		}
-		return out;
-	};
-}
-if (!Object.create) {
-	Object.create = function (proto: any) {
-		function F() {}
-		F.prototype = proto;
-		return new (F as any)();
-	};
-}
-
 if (typeof window === 'undefined') {
 	// Node
 	(global as any).window = global;
diff --git a/testclient-beta.html b/testclient-beta.html
index 7f94986482..4771cfa422 100644
--- a/testclient-beta.html
+++ b/testclient-beta.html
@@ -54,6 +54,7 @@ <h3><button class="closebutton" tabindex="-1" aria-label="Close"><i class="fa fa
 	<script src="https://play.pokemonshowdown.com/config/config.js"></script>
 	<script src="config/testclient-key.js"></script>
 	<script src="js/client-core.js"></script>
+	<script nomodule src="/js/lib/ps-polyfill.js"></script>
 
 	<script src="js/battle-dex.js"></script>
 	<script src="js/battle-text-parser.js"></script>
diff --git a/testclient.html b/testclient.html
index 5ceebb7019..c487305290 100644
--- a/testclient.html
+++ b/testclient.html
@@ -68,6 +68,7 @@ <h3><button class="closebutton" tabindex="-1" aria-label="Close"><i class="fa fa
 		<script>
 			document.getElementById('loading-message').innerHTML += ' DONE<br />Loading libraries...';
 		</script>
+		<script nomodule src="/js/lib/ps-polyfill.js"></script>
 		<script src="js/lib/jquery-2.1.4.min.js"></script>
 		<script src="js/lib/jquery-cookie.js"></script>
 		<script src="js/lib/autoresize.jquery.min.js"></script>