Use byteOffset and byteLength in DataView constructor (fixes #2)

base85.js

@@ -43,7 +43,7 @@ export function encode(ui8a, charset) {
     const last5Length = remain ? remain + 1 : 0;
     const length = Math.ceil(ui8a.length * 5 / 4);
     const target = new Uint8Array(length);
-    const dw = new DataView(ui8a.buffer);
+    const dw = new DataView(ui8a.buffer, ui8a.byteOffset, ui8a.byteLength);
     const to = Math.trunc(ui8a.length / 4);
     for (let i = 0; i < to; i++) {
         let num = dw.getUint32(4 * i);

base85.ts

@@ -52,7 +52,7 @@ export function encode(ui8a: Uint8Array, charset?: "ascii85" | "z85" | CharSet):
     const length = Math.ceil(ui8a.length * 5 / 4);
     const target = new Uint8Array(length);
 
-    const dw = new DataView(ui8a.buffer);
+    const dw = new DataView(ui8a.buffer, ui8a.byteOffset, ui8a.byteLength);
     const to = Math.trunc(ui8a.length / 4);
     for (let i = 0; i < to; i++) {
         let num = dw.getUint32(4 * i);

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@alttiri/base85",
-  "version": "1.7.6",
+  "version": "1.8.0",
   "description": "Pretty fast base85 JavaScript library",
   "homepage": "https://github.com/alttiri/base85",
   "keywords": [

tests/test-4-offset-ab.js

@@ -0,0 +1,21 @@
+import {Tester} from "@alttiri/util-node-js";
+import {encode} from "../base85.js";
+
+const {t} = new Tester().destructible();
+
+const a = [0x00, 0x86, 0x4F, 0xD2, 0x6F, 0xB5, 0x59, 0xF7, 0x5B];
+const newA1 = new Uint8Array(a).slice(1);
+const newA2 = new Uint8Array(a).subarray(1);
+
+// console.log(newA1);
+// console.log(newA2);
+// console.log(encode(newA1));
+// console.log(encode(newA2));
+
+// Uint8Array(8) [134, 79, 210, 111, 181, 89, 247, 91]
+// HelloWorld
+
+t({
+    expect: true,
+    result: encode(newA1) === encode(newA2),
+});