From 66d08e2f06fc28506c6d1a9e7fc86e524d43f0a3 Mon Sep 17 00:00:00 2001
From: Junyoung Choi <fluke8259@gmail.com>
Date: Mon, 26 Nov 2018 15:44:03 +0900
Subject: [PATCH] Include instruction how to extend vfiles

---
 types/vfile/readme.md | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 types/vfile/readme.md

diff --git a/types/vfile/readme.md b/types/vfile/readme.md
new file mode 100644
index 0000000000..349503cef8
--- /dev/null
+++ b/types/vfile/readme.md
@@ -0,0 +1,32 @@
+## VFile typescript Docs
+
+Below are some examples of how to use these Definitions.<br>
+Scenarios where the Typescript code is identical to plain Javascript code are omitted.
+
+### Extending VFile
+
+```ts
+import vfile = require('vfile')
+
+// 1. Define extended vfile interface
+interface CustomVFile extends vfile.VFile {
+    custom: string;
+    data: {
+        custom: number;
+    };
+}
+
+// 2. Provide the extended interface to generic type parameter
+// So it can be used for return value
+const file: CustomVFile = vfile<CustomVFile>({
+    path: '~/example.txt',
+    contents: 'Alpha *braavo* charlie.',
+    custom: 'Custom tango',
+    data: {
+        custom: 12345
+    }
+});
+
+// vfile recognize extended VFile values. So it will return same type.
+const copiedFile: CustomVFile = vfile(file);
+```