utils: use built-in Uint8Array toHex / fromHex when available

Author: paulmillr

src/abstract/utils.ts

@@ -33,15 +33,34 @@ export function abool(title: string, value: boolean): void {
   if (typeof value !== 'boolean') throw new Error(title + ' boolean expected, got ' + value);
 }
 
+export function numberToHexUnpadded(num: number | bigint): string {
+  const hex = num.toString(16);
+  return hex.length & 1 ? '0' + hex : hex;
+}
+
+export function hexToNumber(hex: string): bigint {
+  if (typeof hex !== 'string') throw new Error('hex string expected, got ' + typeof hex);
+  return hex === '' ? _0n : BigInt('0x' + hex); // Big Endian
+}
+
+// Built-in hex conversion https://caniuse.com/mdn-javascript_builtins_uint8array_fromhex
+const hasHexBuiltin: boolean =
+  // @ts-ignore
+  typeof Uint8Array.from([]).toHex === 'function' && typeof Uint8Array.fromHex === 'function';
+
 // Array where index 0xf0 (240) is mapped to string 'f0'
 const hexes = /* @__PURE__ */ Array.from({ length: 256 }, (_, i) =>
   i.toString(16).padStart(2, '0')
 );
+
 /**
+ * Convert byte array to hex string. Uses built-in function, when available.
  * @example bytesToHex(Uint8Array.from([0xca, 0xfe, 0x01, 0x23])) // 'cafe0123'
  */
 export function bytesToHex(bytes: Uint8Array): string {
   abytes(bytes);
+  // @ts-ignore
+  if (hasHexBuiltin) return bytes.toHex();
   // pre-caching improves the speed 6x
   let hex = '';
   for (let i = 0; i < bytes.length; i++) {
@@ -50,16 +69,6 @@ export function bytesToHex(bytes: Uint8Array): string {
   return hex;
 }
 
-export function numberToHexUnpadded(num: number | bigint): string {
-  const hex = num.toString(16);
-  return hex.length & 1 ? '0' + hex : hex;
-}
-
-export function hexToNumber(hex: string): bigint {
-  if (typeof hex !== 'string') throw new Error('hex string expected, got ' + typeof hex);
-  return hex === '' ? _0n : BigInt('0x' + hex); // Big Endian
-}
-
 // 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(ch: number): number | undefined {
@@ -70,10 +79,13 @@ function asciiToBase16(ch: number): number | undefined {
 }
 
 /**
+ * Convert hex string to byte array. Uses built-in function, when available.
  * @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);
+  // @ts-ignore
+  if (hasHexBuiltin) return Uint8Array.fromHex(hex);
   const hl = hex.length;
   const al = hl / 2;
   if (hl % 2) throw new Error('hex string expected, got unpadded hex of length ' + hl);