Refactor a bit

index.ts

@@ -1,30 +1,57 @@
 /*! micro-password-generator - MIT License (c) 2022 Paul Miller (paulmillr.com) */
 export type Bytes = Uint8Array;
 
+function isBytes(a: unknown): a is Uint8Array {
+  return (
+    a instanceof Uint8Array ||
+    (a != null && typeof a === 'object' && a.constructor.name === 'Uint8Array')
+  );
+}
+
 // generic utils
-const hexes = Array.from({ length: 256 }, (v, i) => i.toString(16).padStart(2, '0'));
-function bytesToHex(uint8a: Uint8Array): string {
+// Array where index 0xf0 (240) is mapped to string 'f0'
+const hexes = /* @__PURE__ */ Array.from({ length: 256 }, (_, i) =>
+  i.toString(16).padStart(2, '0')
+);
+/**
+ * @example bytesToHex(Uint8Array.from([0xca, 0xfe, 0x01, 0x23])) // 'cafe0123'
+ */
+export function bytesToHex(bytes: Uint8Array): string {
+  if (!isBytes(bytes)) throw new Error('Uint8Array expected');
   // pre-caching improves the speed 6x
-  if (!(uint8a instanceof Uint8Array)) throw new Error('Uint8Array expected');
   let hex = '';
-  for (let i = 0; i < uint8a.length; i++) {
-    hex += hexes[uint8a[i]];
+  for (let i = 0; i < bytes.length; i++) {
+    hex += hexes[bytes[i]];
   }
   return hex;
 }
 
-function hexToBytes(hex: string): Uint8Array {
-  if (typeof hex !== 'string') {
-    throw new TypeError('hexToBytes: expected string, got ' + typeof hex);
-  }
-  if (hex.length % 2) throw new Error('hexToBytes: received invalid unpadded hex');
-  const array = new Uint8Array(hex.length / 2);
-  for (let i = 0; i < array.length; i++) {
-    const j = i * 2;
-    const hexByte = hex.slice(j, j + 2);
-    const byte = Number.parseInt(hexByte, 16);
-    if (Number.isNaN(byte) || byte < 0) throw new Error('Invalid byte sequence');
-    array[i] = byte;
+// We use optimized technique to convert hex string to byte array
+const asciis = { _0: 48, _9: 57, _A: 65, _F: 70, _a: 97, _f: 102 } as const;
+function asciiToBase16(char: number): number | undefined {
+  if (char >= asciis._0 && char <= asciis._9) return char - asciis._0;
+  if (char >= asciis._A && char <= asciis._F) return char - (asciis._A - 10);
+  if (char >= asciis._a && char <= asciis._f) return char - (asciis._a - 10);
+  return;
+}
+
+/**
+ * @example hexToBytes('cafe0123') // Uint8Array.from([0xca, 0xfe, 0x01, 0x23])
+ */
+export function hexToBytes(hex: string): Uint8Array {
+  if (typeof hex !== 'string') throw new Error('hex string expected, got ' + typeof hex);
+  const hl = hex.length;
+  const al = hl / 2;
+  if (hl % 2) throw new Error('padded hex string expected, got unpadded hex of length ' + hl);
+  const array = new Uint8Array(al);
+  for (let ai = 0, hi = 0; ai < al; ai++, hi += 2) {
+    const n1 = asciiToBase16(hex.charCodeAt(hi));
+    const n2 = asciiToBase16(hex.charCodeAt(hi + 1));
+    if (n1 === undefined || n2 === undefined) {
+      const char = hex[hi] + hex[hi + 1];
+      throw new Error('hex string expected, got non-hex character "' + char + '" at index ' + hi);
+    }
+    array[ai] = n1 * 16 + n2;
   }
   return array;
 }

package.json

@@ -41,10 +41,5 @@
     "macos",
     "secure"
   ],
-  "funding": [
-    {
-      "type": "individual",
-      "url": "https://paulmillr.com/funding/"
-    }
-  ]
+  "funding": "https://paulmillr.com/funding/"
 }

tsconfig.json

@@ -1,23 +1,25 @@
 {
   "compilerOptions": {
-    "strict": true,
-    "declaration": true,
-    "declarationMap": true,
     "target": "es2020",
     "lib": ["es2020"],
-    "module": "node16",
-    "moduleResolution": "node16",
-    "outDir": ".",
-    "noImplicitAny": true,
-    "preserveConstEnums": true,
-    "resolveJsonModule": true,
+    "strict": true,
+    "sourceMap": false,
+    "allowSyntheticDefaultImports": false,
+    "allowUnreachableCode": false,
+    "esModuleInterop": false,
+    "noFallthroughCasesInSwitch": true,
+    "noImplicitReturns": true,
+    "noUncheckedIndexedAccess": false,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
     "baseUrl": ".",
+
+    "module": "es2020",
+    "outDir": ".",
+    "moduleResolution": "bundler",
+    "declaration": true,
+    "declarationMap": true
   },
-  "include": [
-    "index.ts"
-  ],
-  "exclude": [
-    "node_modules",
-    "lib"
-  ]
-}
+  "include": ["index.ts"],
+  "exclude": ["node_modules", "lib"]
+}