bench: add benchmark to utils/async/series-waterfall

lib/node_modules/@stdlib/utils/async/series-waterfall/benchmark/benchmark.js

@@ -0,0 +1,82 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var bench = require( '@stdlib/bench' );
+var pkg = require( './../package.json' ).name;
+var waterfall = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+	var fcns;
+	var i;
+
+	fcns = [ foo, bar, fun ];
+
+	i = 0;
+	b.tic();
+
+	return next();
+
+	function next( error ) {
+		i += 1;
+		if ( error ) {
+			b.fail( 'should not return an error' );
+		}
+		if ( i <= b.iterations ) {
+			return waterfall( fcns, done );
+		}
+		b.toc();
+		b.pass( 'benchmark finished' );
+		b.end();
+	}
+
+	function foo( clbk ) {
+		setTimeout( onTimeout, 0 );
+		function onTimeout() {
+			clbk( null, 'beep' );
+		}
+	}
+
+	function bar( str, clbk ) {
+		setTimeout( onTimeout, 0 );
+		function onTimeout() {
+			clbk( null, str + ' boop' );
+		}
+	}
+
+	function fun( str, clbk ) {
+		setTimeout( onTimeout, 0 );
+		function onTimeout() {
+			clbk( null );
+		}
+	}
+
+	function done( error ) {
+		if ( error ) {
+			next( error );
+			return;
+		}
+		next();
+	}
+});

lib/node_modules/@stdlib/utils/async/series-waterfall/package.json

@@ -15,6 +15,7 @@
   ],
   "main": "./lib",
   "directories": {
+    "benchmark": "./benchmark",
     "doc": "./docs",
     "example": "./examples",
     "lib": "./lib",