initial commit

[squeep-base64url] / lib / base64url.js

diff --git a/lib/base64url.js b/lib/base64url.js
new file mode 100644 (file)
index 0000000..9a494c0
--- /dev/null
+++ b/lib/base64url.js
@@ -0,0 +1,50 @@
+'use strict';
+
+const reEqual = /=/g;
+const rePlus = /\+/g;
+const reSlash = /\//g;
+const reDash = /-/g;
+const reUnder = /_/g;
+const blockSize = 4;
+
+/**
+ * Convert Base64 to Base64URL.
+ * @param {String} input
+ * @returns {String}
+ */
+const base64ToBase64URL = (input) => {
+  return input
+    .replace(reEqual, '')
+    .replace(rePlus, '-')
+    .replace(reSlash, '_');
+};
+
+/**
+ * Convert Base64URL to normal Base64.
+ * @param {String} input
+ * @returns {String}
+ */
+const base64URLToBase64 = (input) => {
+  return base64RePad(input)
+    .replace(reDash, '+')
+    .replace(reUnder, '/');
+};
+
+/**
+ * Add any missing trailing padding which may have been removed from Base64URL encoding.
+ * @param {String} input
+ */
+const base64RePad = (input) => {
+  const lastBlockSize = input.length % blockSize;
+  if (lastBlockSize) {
+    const missing = blockSize - lastBlockSize;
+    return input + '='.repeat(missing);
+  }
+  return input;
+};
+
+module.exports = {
+  base64ToBase64URL,
+  base64URLToBase64,
+  base64RePad,
+}