Hello. In this tutorial, we will explain the concept of pagination in a node.js application.
1. Introduction
Pagination is a concept of adding numbers to identify the sequence of pages. In pagination, we use the skip and limit key for reducing the size of data retrieved from the database. In this tutorial, we will implement pagination in the simplest terms i.e. without the help of a database.
1.1 Setting up Node.js
To set up Node.js on windows you will need to download the installer from this link. Click on the installer (also include the NPM package manager) for your platform and run the installer to start with the Node.js setup wizard. Follow the wizard steps and click on Finish when it is done. If everything goes well you can navigate to the command prompt to verify if the installation was successful as shown in Fig. 1.
2. How to do pagination in Node.js
To set up the application, we will need to navigate to a path where our project will reside. For programming stuff, I am using Visual Studio Code as my preferred IDE. You’re free to choose the IDE of your choice.
2.1 Setting up the implementation
Let us write the different files which will be required for practical learning.
2.2.1 Setting up dependencies
Navigate to the project directory and run npm init -y to create a package.json file. This file holds the metadata relevant to the project and is used for managing the project dependencies, script, version, etc. Add the following code to the file wherein we will specify the required dependencies.
package.json
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 | { "name": "nodejs-pagination", "version": "1.0.0", "description": "", "main": "index.js", "scripts": { "dev": "nodemon server.js", "test": "echo \"Error: no test specified\" && exit 1" }, "keywords": [], "author": "", "license": "ISC", "dependencies": { "express": "^4.17.1" }, "devDependencies": { "nodemon": "^2.0.15" }} |
To download the dependencies navigate to the directory path containing the file and use the npm install command. If everything goes well the dependencies will be loaded inside the node_modules folder and you are good to go with the further steps.
2.2.2 Creating an index file
Add the code to the index file that will consist of the API endpoints to understand the pagination in detail. We will be using a dummy users project for a better understanding.
server.js
001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 | const express = require("express");const app = express();const users = [ { id: 1, full_name: "Kendre Abelevitz" }, { id: 2, full_name: "Rona Walas" }, { id: 3, full_name: "Myrtle Baser" }, { id: 4, full_name: "Washington Walklot" }, { id: 5, full_name: "Jo De Domenici" }, { id: 6, full_name: "Lief Mungham" }, { id: 7, full_name: "Raquel Donlon" }, { id: 8, full_name: "Vivien Wedmore." }, { id: 9, full_name: "Andrei Hubach" }, { id: 10, full_name: "Coral Bunney" }, { id: 11, full_name: "Lanny Simco" }, { id: 12, full_name: "Loralie Bransdon" }, { id: 13, full_name: "Rad Aubert" }, { id: 14, full_name: "Kit Branno" }, { id: 15, full_name: "Quillan Bondar" }, { id: 16, full_name: "Averil Dafforne" }, { id: 17, full_name: "Caroljean Grattan" }, { id: 18, full_name: "Abbie McCurtin" }, { id: 19, full_name: "Rosalia Plowell" }, { id: 20, full_name: "Juli Grieve" }];// get all resultsapp.get("/users", (req, res) => { res.json(users);});// get paginated resultsapp.get("/users/paginate", paginatedResults(users), (req, res) => { res.json(res.paginatedResults);});function paginatedResults(model) { // middleware function return (req, res, next) => { const page = parseInt(req.query.page); const limit = parseInt(req.query.limit); // calculating the starting and ending index const startIndex = (page - 1) * limit; const endIndex = page * limit; const results = {}; if (endIndex < model.length) { results.next = { page: page + 1, limit: limit }; } if (startIndex > 0) { results.previous = { page: page - 1, limit: limit }; } results.results = model.slice(startIndex, endIndex); res.paginatedResults = results; next(); };}const port = 3006;app.listen(port, () => { console.log("Service endpoint= %s", url);}); |
3. Run the Application
To run the application navigate to the project directory and enter the following command as shown in Fig. 2. If everything goes well the application will be started successfully on a port number – 3006.
4. Demo
You are free to use postman or any other tool of your choice to make the HTTP request to the application endpoints.
Endpoints
1 2 3 4 5 6 7 | // get users// HTTP GET//get users (pagination)// HTTP GET |
That is all for this tutorial and I hope the article served you with whatever you were looking for. Happy Learning and do not forget to share!
5. Summary
In this tutorial, we learned about the pagination concepts and sample application to see how it is used practically. You can download the source code and the postman collection from the Downloads section.
6. Download the Project
This was a tutorial to implement pagination in the nodejs application.
You can download the full source code of this example here: How to do pagination in Node.js
