perf: move encodeLatin1 to a separate method

Author: ChALkeR

base64.js

@@ -125,16 +125,11 @@ if (Uint8Array.fromBase64) {
         if (ASCII_WHITESPACE.test(str)) throw new SyntaxError(E_CHAR) // all other chars are checked natively
       }
 
-      let raw
       try {
-        raw = atob(str)
+        arr = ascii.encodeLatin1(atob(str))
       } catch {
         throw new SyntaxError(E_CHAR) // convert atob errors
       }
-
-      const length = raw.length
-      arr = new Uint8Array(length)
-      for (let i = 0; i < length; i++) arr[i] = raw.charCodeAt(i)
     } else {
       return js.fromBase64(str, isBase64url) // early return to skip last chunk verification, it's already validated in js
     }

fallback/ascii.js

@@ -48,3 +48,10 @@ export function decode(arr, start = 0, stop = arr.length) {
   const sliced = start === 0 && stop === arr.length ? arr : arr.subarray(start, stop)
   return String.fromCharCode.apply(String, sliced)
 }
+
+export function encodeLatin1(str) {
+  const length = str.length
+  const arr = new Uint8Array(length)
+  for (let i = 0; i < length; i++) arr[i] = str.charCodeAt(i)
+  return arr
+}