feat(std/encoding): add base64url module (#5976)

1 files changed, 45 insertions, 0 deletions

diff --git a/std/encoding/base64url.ts b/std/encoding/base64url.ts
new file mode 100644
index 000000000..726ea2eb8
--- /dev/null
+++ b/std/encoding/base64url.ts
@@ -0,0 +1,45 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import {
+  decode as convertBase64ToArrayBuffer,
+  encode as convertArrayBufferToBase64,
+} from "./base64.ts";
+
+/*
+ * Some variants allow or require omitting the padding '=' signs:
+ * https://en.wikipedia.org/wiki/Base64#URL_applications
+ */
+export function addPaddingToBase64url(base64url: string): string {
+  if (base64url.length % 4 === 2) return base64url + "==";
+  if (base64url.length % 4 === 3) return base64url + "=";
+  if (base64url.length % 4 === 1)
+    throw new TypeError("Illegal base64url string!");
+  return base64url;
+}
+
+function convertBase64urlToBase64(base64url: string): string {
+  return addPaddingToBase64url(base64url)
+    .replace(/\-/g, "+")
+    .replace(/_/g, "/");
+}
+
+function convertBase64ToBase64url(base64: string): string {
+  return base64.replace(/=/g, "").replace(/\+/g, "-").replace(/\//g, "_");
+}
+
+/**
+ * Converts given data with base64url encoding.
+ * Removes paddings '='.
+ * @param data input to encode
+ */
+export function encode(data: string | ArrayBuffer): string {
+  return convertBase64ToBase64url(convertArrayBufferToBase64(data));
+}
+
+/**
+ * Converts given base64url encoded data back to original
+ * @param data input to decode
+ */
+export function decode(data: string): ArrayBuffer {
+  return convertBase64ToArrayBuffer(convertBase64urlToBase64(data));
+}