In Part 1 to 4, we went through solidity to develop smart contract in Remix, setup development environment, created unit testing methods for smart contract, created a front-end application with Node.js to interact with smart contracts. Now, we will deploy smart contract using truffle and infura. Also, will deploy Node.js application to Heroku.
Category: Node.js
Creating Web App for Smart Contract [Full Stack Ethereum Dapp Part-4]
In Part-3, we created unit test methods for smart contract. Now, we will create a simple webpage to interact with the smart contract. The goal is to create a page with a textbox to enter name, buttons to save name and to get message.
JavaScript: Select Date Time with Timezone
This tutorial explains how to implement to get a JavaScript date object from user selected date time & timezone and the date object can be sent server side to save or for further processing. HTML5 provides input type datetime-local allows user to enter both a date and a time and the user’s local time zone is used. For simplicity, Let’s enhance this to allow user to select any timezone. We are going to use Moment-Timezone library.
JavaScript Async/Await: Serial, Parallel and Complex Flow
If you have experience on ASP.NET MVC then probably you are familiar with async/await keywords in C#. The same thing is now in JavaScript. Before that, Callbacks and Promises are used for asynchronous code. Async/await is built on top of promises and non blocking. The power of Async/await provides asynchronous code look like synchronous code. In this article, we will go through serial/chain and parallel flow and implement a complex flow using Async/Await.
Read Also: JavaScript Promises: Understanding Error Handling with Example
Visual Studio Code: Debugging ES6 Mocha tests with Babel
In my post, I explained how to test server side REST APIs in Node.js using Mocha, Sinon and Chai. I used ES6 test methods for this and Babel is used to execute it. As test methods are executed at development end, so NO need to transpile ES6 to ES5 first and then debug the converted files. You can directly debug ES6 code with Babel.
API Versioning, Express Routers and Node.js
Do you want to set up an API versioning in Node.js and Express environment? This tutorial explains the different ways to do REST API versioning step by step. We will implement the following routing for the versioning:
GET /api/v1.0/
POST /api/v1.0/
GET /api/v2.0/
POST /api/v2.0/
Node.js: Traversing A Directory Recursively with Limited Depth
In this post, we will implement to get all files recursively in a directory using Node.js. Also, will restrict it to traverse directory with limited recursively depth.
Before we get started, consider the following directory structure(For simplicity, the name is according to their depth level i.e. folder 1, sub folder 1.1, sub sub folder 1.1.1…etc):
1 > 1.1 > 1.1.1> 1.1.1.1 > 1.1.1.1.1 2 > 2.1 > 2.1.1 > 2.2
Each directory has txt file with same directory name(means 1.1 will have 1.1.txt file).
Node.js: Sinon Stub and Passport Authenticate
In my last post, I spent some hours to create a stub to skip passport.authenticate method for REST API testing. So, I decided to write a separate post on the same. Before we get started, let’s take a look on how auth middleware is implemented:
Node.js: REST API Testing using Mocha, Sinon and Chai
In my recent post, I covered how to implement token based authentication using Passport, JWT and bcrypt. Let’s extend this post and look into testing REST APIs or server side methods in Node.js using Mocha, Chai and Sinon.
Mocha: It is a test runner to execute our tests.
keywords in code = Describe, It, before, after…etc
Chai: It is an assertion library and allows to write code like writing regular english.
keywords in code = should, assert..etc.
Sinon: It provides test spies (fake functions to track executions), stubs (replace functions with our fake implementation) and mocks (predefined fake method with behaviour).
JavaScript: Null vs Undefined vs Undeclared
For a beginner, it is painful to understand two distinct things null & undefined in JavaScript and use them properly. I noticed many people consider and treat undeclared variable as undefined which is wrong perception. In this article, we will go through null, undefined, empty, NaN and undeclared variables and see how to handle them in different conditions.
Token Based Authentication with Node.js, Express, Mongoose and Passport
This tutorial explains how to implement REST API and Token based authentication in Node.js, Express, Mongoose environment. We are going to use JWT (JSON Web Token) + bcrypt (password hashing algo)+ Passport (authentication middleware to integrate different login strategies) combination. So jsonwebtoken, bcrypt-nodejs and passport-jwt javascript libraries will be used. It is assumed you are familiar with Node.js, MongoDB and ES6 basics.
Deploying a MEAN App to Azure App Services via GitHub
Do you want to setup your MEAN stack (MongoDB, Express, AngularJS and Node.js) application on Azure App Services with Continuous Integration and Delivery? Here are step by step videos to deploy a MEAN application to Azure Web Apps via GitHub and store the app’s data inside Cosmos DB (a drop-in replacement for MongoDB).
Node.js: Simple TCP Server & Client and Promisify the Client
In this post, you will see an example of simple TCP server and client in traditional javascript way and in ES6 way. Node.js has net module which provides an asynchronous network API for creating stream-based TCP or IPC servers and clients. We are going to use it to implement TCP server and client. This post is updated with Node v6.11.2.
nvm-windows: Node or NPM not recognized after nvm installed
To manage multiple Node.js versions on windows, you are going to use and install node-windows. After installation, you run following commands to setup specific node version:
d:\>nvm install 4.7.2 d:\>nvm use 4.7.2 d:\>node --version
and if you get following message
‘node’ is not recognized as an internal or external command, operable program or batch file.
then read this post to troubleshoot the issue.
Visual Studio Code: Setting Environment Variable for Tasks
Visual Studio Code (VSCode) is a lightweight, open-source code editor and available on Linux, Mac OSX, and Windows. One of the key features of Visual Studio Code is its great debugging support for Node.js (JavaScript and TypeScript) and another feature is to run Tasks(Grunt, Gulp, MSBuild…etc.) from the IDE. If you are new to VSCode, I would recommend to see following video which shows how to debug Node.js app, put break-point and use watch window, use environment variable in Visual Studio Code editor: