res.app This property holds a reference to the instance of the Express application that is using the middleware. res.app is identical to the req.app property in the request object.

How should I structure my application? There is no definitive answer to this question. The answer depends on the scale of your application and the team that is involved. To be as flexible as possible, Express makes no assumptions in terms of structure. Routes and other application-specific logic can live in as many files as you wish, in any directory structure you prefer. View the following examples for inspiration: Route listings Route map MVC style controllers Also, there are third-party ex

req.xhr A Boolean property that is true if the request’s X-Requested-With header field is “XMLHttpRequest”, indicating that the request was issued by a client library such as jQuery. req.xhr // => true

Overview Express 4 is a breaking change from Express 3, so. That means an existing Express 3 app will not work if you update the Express version in its dependencies. This article covers: Changes in Express 4. An example of migrating an Express 3 app to Express 4. Upgrading to the Express 4 app generator. Changes in Express 4 There are several significant changes in Express 4: Changes to Express core and middleware system. The dependencies on Connect and built-in middleware were removed, so

req.params This property is an object containing properties mapped to the named route “parameters”. For example, if you have the route /user/:name, then the “name” property is available as req.params.name. This object defaults to {}. // GET /user/tj req.params.name // => "tj" When you use a regular expression for the route definition, capture groups are provided in the array using req.params[n], where n is the nth capture group. This rule is applied to unnamed wild card matches with string

app.put(path, callback [, callback ...]) Routes HTTP PUT requests to the specified path with the specified callback functions. For more information, see the routing guide. You can provide multiple callback functions that behave just like middleware, except that these callbacks can invoke next('route') to bypass the remaining route callback(s). You can use this mechanism to impose pre-conditions on a route, then pass control to subsequent routes if there’s no reason to proceed with the current r

Routing refers to determining how an application responds to a client request to a particular endpoint, which is a URI (or path) and a specific HTTP request method (GET, POST, and so on). Each route can have one or more handler functions, which are executed when the route is matched. Route definition takes the following structure: app.METHOD(PATH, HANDLER) Where: app is an instance of express. METHOD is an HTTP request method. PATH is a path on the server. HANDLER is the function executed

Assuming you’ve already installed Node.js, create a directory to hold your application, and make that your working directory. $ mkdir myapp $ cd myapp Use the npm init command to create a package.json file for your application. For more information on how package.json works, see Specifics of npm’s package.json handling. $ npm init This command prompts you for a number of things, such as the name and version of your application. For now, you can simply hit RETURN to accept the defaults for mos

router.all(path, [callback, ...] callback) This method is just like the router.METHOD() methods, except that it matches all HTTP methods (verbs). This method is extremely useful for mapping “global” logic for specific path prefixes or arbitrary matches. For example, if you placed the following route at the top of all other route definitions, it would require that all routes from that point on would require authentication, and automatically load a user. Keep in mind that these callbacks do not h

res.download(path [, filename] [, fn]) Transfers the file at path as an “attachment”. Typically, browsers will prompt the user for download. By default, the Content-Disposition header “filename=” parameter is path (this typically appears in the browser dialog). Override this default with the filename parameter. When an error ocurrs or transfer is complete, the method calls the optional callback function fn. This method uses res.sendFile() to transfer the file. res.download('/report-12345.pdf');