util: improve spliceOne perf

benchmark/util/splice-one.js

@@ -0,0 +1,22 @@
+'use strict';
+
+const common = require('../common');
+
+const bench = common.createBenchmark(main, {
+  n: [1e7],
+  size: [10, 100, 500],
+}, { flags: ['--expose-internals'] });
+
+function main({ n, size, type }) {
+  const { spliceOne } = require('internal/util');
+  const arr = new Array(size);
+  arr.fill('');
+  const pos = Math.floor(size / 2);
+
+  bench.start();
+  for (var i = 0; i < n; i++) {
+    spliceOne(arr, pos);
+    arr.push('');
+  }
+  bench.end(n);
+}

lib/internal/util.js

@@ -322,10 +322,11 @@ function join(output, separator) {
   return str;
 }
 
-// About 1.5x faster than the two-arg version of Array#splice().
+// Depending on the size of the array, this is anywhere between 1.5-10x
+// faster than the two-arg version of Array#splice()
 function spliceOne(list, index) {
-  for (var i = index, k = i + 1, n = list.length; k < n; i += 1, k += 1)
-    list[i] = list[k];
+  for (; index + 1 < list.length; index++)
+    list[index] = list[index + 1];
   list.pop();
 }