Express.js | app.render() Function Last Updated : 08 Jan, 2025 Comments Improve Suggest changes Like Article Like Report The app.render() function is used to render the HTML of a view via the callback function. This function returns the HTML in the callback function. Syntax:app.render(view, [locals], callback)Parameters:view: It is the name of the HTML page which is to be rendered.locals: It is an optional parameter that is an object containing local variables for the view parameter passed.callback: It is a function that is passed as a parameter.Installation of the express module:You can visit the link to Install the express module. You can install this package by using this command.npm install expressAfter installing the express module, you can check your express version in the command prompt using the command.npm version expressCreate an email.ejs file in the views folder with the following code: Filename: email.ejs html <html> <head> <title>Function Demo</title> </head> <body> <h3>Greetings from GeeksforGeeks</h3> </body> </html> Note: You may use any view engine, in this case, we have used ejs.After that, you can just create a folder and add a file, for example, index.js. To run this file you need to run the following command.node index.jsFilename: index.js javascript const express = require('express'); const app = express(); const PORT = 3000; // View engine setup app.set('view engine', 'ejs'); app.render('email', function (err, html) { if (err) console.log(err); console.log(html); }); app.listen(PORT, function (err) { if (err) console.log("Error in server setup"); console.log("Server listening on Port", PORT); }); Steps to run the program:Make sure you have installed express and ejs modules using the following command:npm install expressnpm install ejsRun the index.js file using the below command:node index.jsOutput: Comment More infoAdvertise with us Next Article Express.js | app.render() Function G gouravhammad Follow Improve Article Tags : JavaScript Web Technologies Node.js Express.js Similar Reads Express.js | app.route() Function The app.route() function returns an instance of a single route, which you can then use to handle HTTP verbs with optional middleware. Use app.route() to avoid duplicate route names (and thus typo errors). Syntax:app.route( path )Installation of the express module:You can visit the link to Install th 2 min read Express.js | app.METHOD() Function The app.METHOD() function is used to route an HTTP request, where METHOD is the HTTP method of the request, such as GET, PUT, POST, and so on, in lowercase. Thus, the actual methods are app.get(), app.post(), app.put(), and so on. Syntax: app.METHOD(path, callback [, callback ...]) Parameters: Path 2 min read Express.js res.append() Function The res.append() function appends the specified value to the HTTP response header field and if the header is not already set then it creates the header with the specified value. Syntax: res.append(field [, value])Parameter: The field parameter describes the name of the field that need to be appended 2 min read Express app.use() Function The app.use() function in Express.js adds middleware to the application's request-processing pipeline. It applies the specified middleware to all incoming requests or to specific routes, allowing you to modify request/response objects, perform operations, or handle errors throughout the application. 3 min read Express.js | app.param() Function The app.param() function is used to add the callback triggers to route parameters. It is commonly used to check for the existence of the data requested related to the route parameter. Syntax: app.param([name], callback) Parameters: name: It is the name of the parameter or an array of them.callback: 2 min read Like