Add typescript typings

index.d.ts

@@ -0,0 +1,18 @@
+import { Request, Response, NextFunction } from "express";
+
+/** Express.js middleware that is responsible for initializing the context for each request. */
+export declare function middleware(
+  req: Request,
+  res: Response,
+  next: NextFunction
+): void;
+
+/**
+ * Gets a value from the context by key.  Will return undefined if the context has not yet been initialized for this request or if a value is not found for the specified key.
+ */
+export declare function get(key: string): any;
+
+/**
+ * Adds a value to the context by key.  If the key already exists, its value will be overwritten.  No value will persist if the context has not yet been initialized.
+ */
+export declare function set(key: string, value: any): void;