Install And Setup React App on Ubuntu
3K- by KnowledgeHut
- 18th Jan, 2021
- Last updated on 11th Mar, 2021
- 7 mins read
React is a JavaScript library for building user interfaces. It is opensource and maintained by Facebook.
You can read more about React here.
In this blog we are going to learn how to install and setup a React App on Ubuntu (version 16 and above).
Prerequisites
This blog assumes that you are using Ubuntu 16 or above versions and you have all the privileges to install the software in the machine, and also have access to the required websites mentioned in the blog.
System Requirements:
- Ubuntu 16 or above
- Minimum 4GB RAM
- Visual Studio Code installed.
Why should we choose React, and what are its advantages?
- React is built on JavaScript which makes it easier to learn and easier to use.
- React is component based which means we can write re-usable components. Start with small things, which you use to build bigger things, which you use to build apps.
- React is lightweight compared to Angular; which in turn makes your application faster to load—which is very important from the user’s point of view.
- React ensures faster rendering of DOM (document object model), this has been achieved by the introduction of Virtual DOM-currently, one of the benefits of using React for heavy loaded and dynamic software solutions.
- React has a helpful and interactive developer toolset which makes it easy to debug. React Developer Tools is a browser extension available for both Chrome and Firefox. It enables developers to observe reactive component hierarchies, discover child and parent components, and inspect their current state and props.
- React uses JSX(JavaScript XML) which has HTML-like syntax, making it easy to code and understand.
- React has strong community support on Github, Stackoverflow and many other platforms.
- React is SEO friendly.
There are certainly many other nice features about using React.
What is Node.js?
Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine. Node.js is an Open Source Server Environment that is free and runs on almost all Operating Systems (Windows, Linux, Unix, Mac OS X, etc.).
You can read more about Nodejs here.
Why do we need Nodejs for React apps?
Node.js lets developers use JavaScript to develop variety of applications like network applications, command line tools, web APIs, mobile applications, web applications etc.
React usually runs on Node Server in development, but we can make use of other Servers likes Apache or Nginix to run React App in production. You do not need NodeJS to run React in production.
What is NPM, why do we need NPM for React apps?
NPM (Node Package Manager) is a dependency management tool for JavaScript applications. It is Open Source and also has command line utility for interacting with the application that aids in package installation, version management, and dependency management.
React does not ship with all the features by itself, so it uses external packages to add the required features to the React application. These packages are maintained by NPM (Node package manager) which is shipped with Nodejs in development.
You can read more about npm here.
We can use yarn instead of NPM during development and production for React apps.
Install Node.js
There are many ways to install Node.js in an Ubuntu machine.
- Install Node.js from the Ubuntu repository
- Install Using a PPA (personal package archive)
Using the first method we will not get the latest version of Node.js installed so we will choose the second method where we will get the latest version of Node.js installed.
Installing Using a PPA (personal package archive)
To get the latest version of Node.js installed on ubuntu, add a PPA (personal package archive). It is maintained by NodeSource.
Open terminal and run below commands:
- Install curl: Run below command on terminal
Command: sudo apt-get install curl
- Set the NodeSource PPA: Run below command on terminal
Command: curl -sL https://deb.nodesource.com/setup_current.x | sudo -E bash –
The PPA will be added to your configuration and your local package cache will be updated automatically.
You can read more about available versions of Node.js in nodesource here.
- Install Node.js: Run the below command on terminal
Command: sudo apt-get install -y nodejs
- Check for Node.js Installation: Run below command on terminal
Command: node -v
It has to show the version of node installed in this case v15.4.0
Now let's see how we can install and setup React app in Ubuntu machine
- Using create-react-app (installing create-react-app using npm)
- Using npx (Recommended in React docs)
Using create-react-app (npm)
In setting up a React project we come across tools like babel and webpack which are not easy to understand and configure for a person who is new to React and JavaScript. There are several tools that help to sort this problem. One of them is create-react-app. This is the easiest to setup. Create-react-app comes with production grade configurations pre-built. You can alter the configurations by ejecting from the create-react-app as well.
Follow the below steps to install using npm create-react-app
- Go into your desired location where you want to start your react app using ‘cd’ command
- Run below command to install create-react-app using npm
Command: npm install -g create-react-app
- Now Run create-react-app on terminal to setup a React-app.
Command: create-react-app hello-world
- This creates a folder with the name hello-world. You can navigate into the folder using ‘cd’ command and look at the project structure.
This gives the React app which we can use, but React recommends using npx.
Using npx command:
npx is the package runner, since npm version 5.2.0 npx is pre-bundled with npm.
Read more about differences npx and npm here.
Follow the below steps to setup using npx.
- Go into your desired location where you want to start your react app using ‘cd’ command
- Run the below command to setup React app using npx
Command: npx create-react-app my-app
That’s it! Your React app is ready with a single command.
- This creates a folder with the name hello-world. You can navigate into the folder using ‘cd’ command.
- Now open the project in vs-code
When you open the project in visual studio code the structure looks like this.
Now let's have a look at the files and folders we have:
- node_modules: This folder is managed by package manager (npm) and contains all the project library dependencies. We should not edit any file inside this folder.
- public: This folder contains the assets that should be served publicly without any restrictions and contains files like index.html, favicon, manifest.json
- src: This is the folder that contains all the files that are used to create web applications. As a react developer you are likely to spend a lot of time in this folder creating components and other sources of code.
- .gitignore: This file has all the assets which should be ignored by git while we publish our code to GitHub eg: node_modules
- package.json: This is a JSON file which has all information about the app such as name, dependencies, scripts we use to run the application etc.
- Readme.md: This is a markdown file where you specify the things which you want to show when someone visits your project on GitHub.
Now let's run our first React app!
- Open the terminal integrated with Visual studio code or just stay in the ubuntu terminal; either is fine. Let's use the integrated terminal.
- Run the app using the following command:
Command: npm start
This opens the app in your favourite browser as shown below:
Now, let's make our first code changes:
On navigating to src folder, you will find App.js file, through which the whole app is run inside the browser. Change the code as you see below and save by hitting ctrl+s.
Now look at the browser where the app is running. It looks like the one in the image below.
Congratulations on making your first React app!
What you have learnt:
- What is React and why it should be used
- What is Node.js, and how it should be installed on Ubuntu.
- What is npm
- What is create-react-app
- How to setup React-app on Ubuntu
- How to run the React-app
- How to make code changes to create your first React application.
React has rapid changes for every new version. It is important to keep yourself updated with the latest releases of React, so that you can make your life as a React developer easier!
KnowledgeHut
KnowledgeHut is an outcome-focused global ed-tech company. We help organizations and professionals unlock excellence through skills development. We offer training solutions under the people and process, data science, full-stack development, cybersecurity, future technologies and digital transformation verticals.
Website : https://www.knowledgehut.com
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Also, take a look at the results:As a result, the nesteddoc collection contains four documents, each of which contains nested documents. The find() method can be used to access the collection's documents.db.nesteddoc.find()Specify Equality Condition:In this example, we will select the document from the nesteddoc query where dept equals “A”.db.nesteddoc.find({dept: "A"})Querying ArraysUse the query document {: } to specify an equality condition on an array, where is the exact array to match, including the order of the elements.The following query looks for all documents where the field tags value is an array with exactly two elements, "S" and "M," in the order specified:db.nesteddoc.find( { sizes: ["S", "M"] } )Use the $all operator to find an array that contains both the elements "S" and "M," regardless of order or other elements in the array:db.nested.find( { sizes: { $all: ["S", "M"] } } )Query an Array for an Element:The following example queries for all documents where size is an array that contains the string “S” as one of its elements:db.nesteddoc.find( { sizes: "S" } )Filter conditionsTo discuss the filter conditions, we will consider a situation that elaborates this. We will start by creating a collection with the name “products” and then add the documents to it.db.products.insertMany([ { _id: 1, item: { name: "ab", code: "123" }, qty: 15, tags: [ "A", "B", "C" ] }, { _id: 2, item: { name: "cd", code: "123" }, qty: 20, tags: [ "B" ] }, { _id: 3, item: { name: "ij", code: "456" }, qty: 25, tags: [ "A", "B" ] }, { _id: 4, item: { name: "xy", code: "456" }, qty: 30, tags: [ "B", "A" ] }, { _id: 5, item: { name: "mn", code: "000" }, qty: 20, tags: [ [ "A", "B" ], "C" ] }])To check the documents, use db.products.find():$gt$gt selects documents with a field value greater than (or equal to) the specified value.db.products.find( { qty: { $gt: “20” } } )$gte:$gte finds documents in which a field's value is greater than or equal to (i.e. >=) a specified value (e.g. value.)db.products.find( { qty: { $gte: 20 } } )$lt:$lt selects documents whose field value is less than (or equal to) the specified value.db.products.find( { qty: { $lt: 25 } } )$lte:$lte selects documents in which the field's value is less than or equal to (i.e. =) the specified value.db.products.find( { qty: { $lte: 20 } } )Query an Array by Array Length:To find arrays with a specific number of elements, use the $size operator. For example, the following selects documents with two elements in the array.db.products.find( { "tags": {$size: 2} } )ProjectionIn MongoDB, projection refers to selecting only the data that is required rather than the entire document's data. If a document has five fields and you only want to show three of them, select only three of them.The find() method in MongoDB accepts a second optional parameter, which is a list of fields to retrieve, as explained in MongoDB Query Document. When you use the find() method in MongoDB, it displays all of a document's fields. To prevent this, create a list of fields with the values 1 or 0. The value 1 indicates that the field should be visible, while 0 indicates that it should be hidden.Syntax:db.COLLECTION_NAME.find({},{KEY:1})Example:We will consider the previous example of products collection. Run the below command on mongoshell to learn how projection works:db.products.find({},{"tags":1, _id:0})Keep in mind that the _id field is always displayed while executing the find() method; if you do not want this field to be displayed, set it to 0.Optimized FindingsTo retrieve a document from a MongoDB collection, use the Find method.Using the Find method, we can retrieve specific documents as well as the fields that we require. Other find methods can also be used to retrieve specific documents based on our needs.By inserting array elements into the query, we can retrieve specific elements or documents. To retrieve data for array elements from the collection in MongoDB, we can use multiple query operators.
6495
- by Abhresh Sugandhi
- 20 Jan 2022
- 8 mins read
MongoDB's find() method selects documents from a c... Read More
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By Abhresh Sugandhi
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MapReduce is a framework for handling parallelizable problems across huge files using a huge number of devices (nodes), which are collectively referred to as a cluster (if all nodes are on the same local network and use similar hardware) or a grid (if the nodes are shared across geographically and administratively distributed systems, and use more heterogeneous hardware). When data stored in a filesystem (unstructured) or a database(structured) is processed, MapReduce can take advantage of data's locality, processing it close to where it's stored to reduce communication costs. Typically, a MapReduce framework (or system) consists of three operations: Map: Each worker node applies the map function to local data and saves the result to a temporary storage. Only one copy of the redundant input data is processed by a master node. Shuffle: worker nodes redistribute data based on output keys (produced by the map function), ensuring that all data associated with a single key is stored on the same worker node. Reduce: each group of output data is now processed in parallel by worker nodes, per key. This article will walk you through the Map-Reduce model's functionality step by step. Map Reduce in MongoDB The map-reduce operation has been deprecated since MongoDB 5.0. An aggregation pipeline outperforms a map-reduce operation in terms of performance and usability. Aggregation pipeline operators like $group, $merge, and others can be used to rewrite map-reduce operations. Starting with version 4.4, MongoDB provides the $accumulator and $function aggregation operators for map-reduce operations that require custom functionality. In JavaScript, use these operators to create custom aggregation expressions. The map and reduce functions are the two main functions here. As a result, the data is independently mapped and reduced in different spaces before being combined in the function and saved to the specified new collection. This mapReduce() function was designed to work with large data sets only. You can perform aggregation operations like max and avg on data using Map Reduce, which is similar to groupBy in SQL. It works independently and in parallel on data. Implementing Map Reduce with Mongosh (MongoDB Shell) The db.collection.mapReduce() method in mongosh is a wrapper for the mapReduce command. The examples that follow make use of the db.collection.mapReduce(). Example: Create a collection ‘orders’ with these documents: db.orders.insertMany([ { _id: 1, cust_id: "Ishan Jain", ord_date: new Date("2021-11-01"), price: 25, items: [ { sku: "oranges", qty: 5, price: 2.5 }, { sku: "apples", qty: 5, price: 2.5 } ], status: "A" }, { _id: 2, cust_id: "Ishan Jain", ord_date: new Date("2021-11-08"), price: 70, items: [ { sku: "oranges", qty: 8, price: 2.5 }, { sku: "chocolates", qty: 5, price: 10 } ], status: "A" }, { _id: 3, cust_id: "Bhavesh Galav", ord_date: new Date("2021-11-08"), price: 50, items: [ { sku: "oranges", qty: 10, price: 2.5 }, { sku: "pears", qty: 10, price: 2.5 } ], status: "A" }, { _id: 4, cust_id: "Bhavesh Galav", ord_date: new Date("2021-11-18"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" }, { _id: 5, cust_id: "Bhavesh Galav", ord_date: new Date("2021-11-19"), price: 50, items: [ { sku: "chocolates", qty: 5, price: 10 } ], status: "A"}, { _id: 6, cust_id: "Madan Parmar", ord_date: new Date("2021-11-19"), price: 35, items: [ { sku: "carrots", qty: 10, price: 1.0 }, { sku: "apples", qty: 10, price: 2.5 } ], status: "A" }, { _id: 7, cust_id: "Madan Parmar", ord_date: new Date("2021-11-20"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" }, { _id: 8, cust_id: "Abhresh", ord_date: new Date("2021-11-20"), price: 75, items: [ { sku: "chocolates", qty: 5, price: 10 }, { sku: "apples", qty: 10, price: 2.5 } ], status: "A" }, { _id: 9, cust_id: "Abhresh", ord_date: new Date("2021-11-20"), price: 55, items: [ { sku: "carrots", qty: 5, price: 1.0 }, { sku: "apples", qty: 10, price: 2.5 }, { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" }, { _id: 10, cust_id: "Abhresh", ord_date: new Date("2021-11-23"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" } ]) Apply a map-reduce operation to the orders collection to group them by cust_id, then add the prices for each cust_id: To process each input document, define the map function: this refers the document that the map-reduce operation is processing in the function. For each document, the function maps the price to the cust_id and outputs the cust_id and price. var mapFunction1 = function() {emit(this.cust_id, this.price);}; With the two arguments keyCustId and valuesPrices, define the corresponding reduce function: The elements of the valuesPrices array are the price values emitted by the map function, grouped by keyCustId. The valuesPrice array is reduced to the sum of its elements by this function. var reduceFunction1 = function(keyCustId, valuesPrices) {return Array.sum(valuesPrices);};Apply the mapFunction1 map function and the reduceFunction1 reduce function to all documents in the orders collection: db.orders.mapReduce(mapFunction1,reduceFunction1,{ out: "map_reduce_example" }) The results of this operation are saved in the map_reduce_example collection. If the map_reduce_example collection already exists, the operation will overwrite its contents with the map-reduce operation's results. Check the map_reduce_example collection to verify: db.map_reduce_example.find().sort( { _id: 1 } ) Aggregation Alternative:You can rewrite the map-reduce operation without defining custom functions by using the available aggregation pipeline operators: db.orders.aggregate([{$group: { _id:"$cust_id",value:{$sum: "$price" } } },{ $out: "agg_alternative_1" }]) Check the agg_alternative_1 collection to verify: db.agg_alternative_1.find().sort( { _id: 1 } )Implementing Map Reduce with Java Consider the collection car and insert the following documents in it. db.car.insert( [ {car_id:"c1",name:"Audi",color:"Black",cno:"H110",mfdcountry:"Germany",speed:72,price:11.25}, {car_id:"c2",name:"Polo",color:"White",cno:"H111",mfdcountry:"Japan",speed:65,price:8.5}, {car_id:"c3",name:"Alto",color:"Silver",cno:"H112",mfdcountry:"India",speed:53,price:4.5}, {car_id:"c4",name:"Santro",color:"Grey",cno:"H113",mfdcountry:"Sweden",speed:89,price:3.5} , {car_id:"c5",name:"Zen",color:"Blue",cno:"H114",mfdcountry:"Denmark",speed:94,price:6.5} ] ) You will get an output like this: Let's now write the map reduce function on a collection of cars, grouping them by speed and classifying them as overspeed cars. var speedmap = function (){ var criteria; if ( this.speed > 70 ) {criteria = 'overspeed';emit(criteria,this.speed);}}; Based on the speed, this function classifies the vehicle as an overspeed vehicle. The term "this" refers to the current document that requires map reduction. var avgspeed_reducemap = function(key, speed) { var total =0; for (var i = 0; i
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- by Abhresh Sugandhi
- 19 Jan 2022
- 9 mins read
Algorithms and applications in today's data-driven... Read More
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