add a rudimentary benchmark

Author: mourner

bench.js

@@ -0,0 +1,22 @@
+import match from './index.js';
+import {PNG} from 'pngjs';
+import fs from 'fs';
+
+const data = [1, 2, 3, 4, 5, 6, 7].map(i => [
+    readImage(`${i}a`),
+    readImage(`${i}b`)
+]);
+
+console.time('match');
+let sum = 0;
+for (let i = 0; i < 100; i++) {
+    for (const [img1, img2] of data) {
+        sum += match(img1.data, img2.data, null, img1.width, img1.height);
+    }
+}
+console.timeEnd('match');
+console.log(sum);
+
+function readImage(name) {
+    return PNG.sync.read(fs.readFileSync(new URL(`test/fixtures/${name}.png`, import.meta.url)));
+}