From cc258af0e4898338b6be49ac79b49dc28169d0c9 Mon Sep 17 00:00:00 2001
From: Shiya Luo <luo.shiya@gmail.com>
Date: Mon, 9 Oct 2017 18:46:14 -0700
Subject: [PATCH] doc: clarify usage of util.promisify.custom

PR-URL: https://github.com/nodejs/node/pull/16134
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 doc/api/util.md | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/doc/api/util.md b/doc/api/util.md
index 2653c01af1d4c9..9cca721e63cc94 100644
--- a/doc/api/util.md
+++ b/doc/api/util.md
@@ -525,6 +525,16 @@ console.log(promisified === doSomething[util.promisify.custom]);
 This can be useful for cases where the original function does not follow the
 standard format of taking an error-first callback as the last argument.
 
+For example, with a function that takes in `(foo, onSuccessCallback, onErrorCallback)`:
+
+```js
+doSomething[util.promisify.custom] = function(foo) {
+  return new Promise(function(resolve, reject) {
+    doSomething(foo, resolve, reject);
+  });
+};
+```
+
 ### util.promisify.custom
 <!-- YAML
 added: v8.0.0