1 files changed, 72 insertions, 0 deletions
diff --git a/ext/node/polyfills/internal/normalize_encoding.mjs b/ext/node/polyfills/internal/normalize_encoding.mjs
new file mode 100644
index 000000000..788c86c56
--- /dev/null
+++ b/ext/node/polyfills/internal/normalize_encoding.mjs
@@ -0,0 +1,72 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+export function normalizeEncoding(enc) {
+  if (enc == null || enc === "utf8" || enc === "utf-8") return "utf8";
+  return slowCases(enc);
+}
+
+export function slowCases(enc) {
+  switch (enc.length) {
+    case 4:
+      if (enc === "UTF8") return "utf8";
+      if (enc === "ucs2" || enc === "UCS2") return "utf16le";
+      enc = `${enc}`.toLowerCase();
+      if (enc === "utf8") return "utf8";
+      if (enc === "ucs2") return "utf16le";
+      break;
+    case 3:
+      if (
+        enc === "hex" || enc === "HEX" ||
+        `${enc}`.toLowerCase() === "hex"
+      ) {
+        return "hex";
+      }
+      break;
+    case 5:
+      if (enc === "ascii") return "ascii";
+      if (enc === "ucs-2") return "utf16le";
+      if (enc === "UTF-8") return "utf8";
+      if (enc === "ASCII") return "ascii";
+      if (enc === "UCS-2") return "utf16le";
+      enc = `${enc}`.toLowerCase();
+      if (enc === "utf-8") return "utf8";
+      if (enc === "ascii") return "ascii";
+      if (enc === "ucs-2") return "utf16le";
+      break;
+    case 6:
+      if (enc === "base64") return "base64";
+      if (enc === "latin1" || enc === "binary") return "latin1";
+      if (enc === "BASE64") return "base64";
+      if (enc === "LATIN1" || enc === "BINARY") return "latin1";
+      enc = `${enc}`.toLowerCase();
+      if (enc === "base64") return "base64";
+      if (enc === "latin1" || enc === "binary") return "latin1";
+      break;
+    case 7:
+      if (
+        enc === "utf16le" || enc === "UTF16LE" ||
+        `${enc}`.toLowerCase() === "utf16le"
+      ) {
+        return "utf16le";
+      }
+      break;
+    case 8:
+      if (
+        enc === "utf-16le" || enc === "UTF-16LE" ||
+        `${enc}`.toLowerCase() === "utf-16le"
+      ) {
+        return "utf16le";
+      }
+      break;
+    case 9:
+      if (
+        enc === "base64url" || enc === "BASE64URL" ||
+        `${enc}`.toLowerCase() === "base64url"
+      ) {
+        return "base64url";
+      }
+      break;
+    default:
+      if (enc === "") return "utf8";
+  }
+}