Add definitions for on-headers (github/jshttp/on-headers)

on-headers/on-headers.d.ts

@@ -0,0 +1,33 @@
+// Type definitions for serve-favicon 2.1.6
+// Project: https://github.com/jshttp/on-headers
+// Definitions by: John Jeffery <https://github.com/jjeffery/>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+/// <reference path="../node/node.d.ts" />
+
+declare module "on-headers" {
+    import http = require("http");
+
+    /**
+     * This will add the listener to fire when headers are emitted for res.
+     * The listener is passed the response object as its context (this).
+     * Headers are considered emitted only once, right before they 
+     * are sent to the client.
+     *
+     * When this is called multiple times on the same res, the listeners
+     * are fired in the reverse order they were added.
+     *
+     * @param res HTTP server response object
+     * @param listener Function to call prior to headers being emitted,
+     *        the response object is passed as this context.
+     */
+    function onHeaders(res: http.ServerResponse, listener: Function):void;
+
+    // Note that this definition might be able to be improved in a future
+    // version of typescript. At the moment it is not possible to declare
+    // the type of the 'this' context for a function, but it might be included
+    // in a future typescript version.
+    // https://github.com/Microsoft/TypeScript/issues/229
+
+    export = onHeaders;
+}