refactor: add uuidPolyfill

Author: Steven-John Lange

packages/node_modules/pouchdb-utils/src/uuid-browser.js

@@ -1,3 +1,41 @@
-export default function uuid() {
-  return crypto.randomUUID();
+function uuidPolyfill() {
+  const buffer = crypto.getRandomValues(new Uint8Array(16));
+
+  // https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_(random)
+  // set bits for version: 4
+  buffer[6] = (buffer[6] & 0x0f) | 0x40;
+  // and variant: 1
+  buffer[8] = (buffer[8] & 0x3f) | 0x80;
+
+  const str = toHex(buffer);
+
+  return str.slice(0, 8) + "-"
+    + str.slice(8, 12) + "-"
+    + str.slice(12, 16) + "-"
+    + str.slice(12, 16) + "-"
+    + str.slice(16, 20) + "-"
+    + str.slice(20);
 }
+
+/**
+ * convert Uint8Array to HEX string
+ * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array/toHex
+ * 
+ * @param {Uint8Array} buffer
+ * @returns {string}
+ */
+function toHex(buffer) {
+  if (typeof buffer.toHex === "function") {
+    return buffer.toHex();
+  }
+
+  let str = "";
+  for (let i = 0; i < buffer.length; ++i) {
+    str += buffer[i].toString(16).padStart(2, "0");
+  }
+  return str;
+}
+
+const uuid = typeof crypto.randomUUID === "function" ? crypto.randomUUID.bind(crypto) : uuidPolyfill;
+
+export default uuid;