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Blockchain Javascript

Job Application For Js Developer At Blockchain

Job Application For Js Developer At Blockchain

By clicking the I Accept button you expressly make the following representations and warranties and give your consents as described below: Blockchain collects your personal data for the purposes of managing Blockchains recruitment related activities as well as for organizational planning purposes globally. Consequently, Blockchain may use your personal data in relation to the evaluation and selection of applicants including for example setting up and conducting interviews and tests, evaluating and assessing the results thereto and as is otherwise needed in the recruitment processes including the final recruitment. Blockchain does not disclose your personal data to unauthorized third parties. However, as a global corporation consisting of multiple affiliated companies in various countries, Blockchain has international sites and Blockchain uses resources located throughout the world. Blockchain may from time to time also use third parties to act on Blockchains behalf. You agree to the fact that to the extent necessary your personal data may be transferred and/or disclosed to any company within Blockchain group of companies as well as to third parties acting on Blockchains behalf, including also transfers to servers and databases outside the country where you provided Blockchain with your personal data. Such transfers may include for example transfers and/or disclosures outside the European Economic Area and in the United States of America. Continue reading >>

Build A Bitcoin Blockchain In Javascript Part1

Build A Bitcoin Blockchain In Javascript Part1

Former professional basketball player turned financial trader. Currently building software at alkami.io and geeking out about crypto. Build A Bitcoin Blockchain In JavaScript Part1 In this tutorial were going to build a dumbed down version of the Bitcoin blockchain. Were going to be using the bitcoin core developer guide as a reference. The goal is to start with something super simple and gradually build and refactor our way up to something super complicated that resembles the Bitcoin blockchain. I decided to use the Bitcoin blockchain because its the most widely used and well known of them all. Im using node version 8.9.3 and npm version 5.5.1. Feel free to leave comments or questions about anything is this tutorial. The block chain provides Bitcoins public ledger, an ordered and timestamped record of transactions. This system is used to protect against double spending and modification of previous transaction records. Lets run these commands in our terminal: So weve created our BitcoinBlockchain directory and added a node_modules directory that only includes the crypto-js library which is JavaScript library of crypto standards. Now lets create our block class inside block.js const SHA256 = require('crypto-js/sha256'); Bitcoin uses a SHA-256 Cryptographic Hash Algorithm which creates a string of text, called a signature, out of any piece of data. Since each one of our blocks is going to be unique, each block is going to generate its own unique hash using its calculateHash() function. The calculateHash() function is going to take each property of a new block, moosh it together into one string and return a SHA-256 hash of that string. Each block has to also reference its previous blocks hash(Header). This ensures a transaction cannot be modified without modifying the blo Continue reading >>

A Blockchain In 200 Lines Ofcode

A Blockchain In 200 Lines Ofcode

I like programming and Careless Whisper. The basic concept of blockchain is quite simple: a distributed database that maintains a continuously growing list of ordered records. However, it is easy to get mixed up as usually when we talk about blockchains we also talk about the problems we are trying to solve with them. This is the case in the popular blockchain-based projects such as Bitcoin and Ethereum . The term blockchain is usually strongly tied to concepts like transactions , smart contracts or cryptocurrencies . This makes understanding blockchains a necessarily harder task, than it must be. Especially source-code-wisely. Here I will go through a super-simple blockchain I implemented in 200 lines of Javascript called NaiveChain . The first logical step is to decide the block structure. To keep things as simple as possible we include only the most necessary: index, timestamp, data, hash and previous hash. The hash of the previous block must be found in the block to preserve the chain integrity The block needs to be hashed to keep the integrity of the data. A SHA-256 is taken over the content of the block. It should be noted that this hash has nothing to do with mining , since there is no Proof Of Work problem to solve. To generate a block we must know the hash of the previous block and create the rest of the required content (= index, hash, data and timestamp). Block data is something that is provided by the end-user. A in-memory Javascript array is used to store the blockchain. The first block of the blockchain is always a so-called genesis-block, which is hard coded. At any given time we must be able to validate if a block or a chain of blocks are valid in terms of integrity. This is true especially when we receive new blocks from other nodes and must decide whe Continue reading >>

How To Create An Application On Blockchain Using Hyperledger

How To Create An Application On Blockchain Using Hyperledger

How to create an application on blockchain using Hyperledger We are going to build a digital bank using Hyperledger Composer. It will have customers and accounts. At the end of it, youll be able to transfer funds and record all transactions on blockchain. Well expose a RESTful API for the same, so that even a person who has no clue what blockchain is can make a beautiful user interface (UI) around it. Well also create this applications UI in Angular. Im super excited to share this step-by-step guide with you. So lets get started right away! Source: When I was first coding this out, I ran into errors. Lots and lots of them. But I think thats good, because it made me learn a lot of things. Errors are essential. I got to a point where I felt switching it on and off would make things better. It almost made me lose my mind, but its an integral part in every hackers life. Before getting started, you need to ensure that the machine youre using is equipped with the required configurations. You may need to download certain prerequisites and set up a basic dev environment. Below are the links to do that. Follow those steps before starting to develop an application, otherwise youll definitely run into stupid errors. First install the Hyperledger composer . Then install the development environment . Theres no need to start Playground while youre installing the environment. Make sure docker is running, and when you run./startFabric.sh its going to take a couple of minutes. So be patient. Now that your machine is all set, we can start coding! Source: Our Business Network Definition (BND) consists of the data model, transaction logic, and access control rules. The data model and access control rules are coded in domain specific language (which is very simple to catch up with). The tr Continue reading >>

With A Great Language Comes Great Usability: Making Blockchain More Accessible With Javascript

With A Great Language Comes Great Usability: Making Blockchain More Accessible With Javascript

Interview with Will Clark, Full Stack Developer at Lisk With a great language comes great usability: Making blockchain more accessible with JavaScript JavaScript is seen as the go-to language for newcomers to learn programming; meanwhile, blockchain still has this hard to understand label attached to its name. JavaScript is not always the right choice for blockchain projects, though. For Lisk, it ensures wide platform adoption. Heres how. JAXenter: Lisk is written in JavaScript using NodeJS. But why JavaScript and not another language? What does it have that Java doesnt? Will Clark: Our mission at Lisk is to make blockchain technology accessible to all. Choosing JavaScript as Lisks main programming language ensures wide platform adoption once the tools are released. JavaScript is increasingly seen as the go-to language for newcomers to learn programming, with a lot of focus from major industry players in recent years Facebook, Microsoft, Google and so on. The community behind this language has a very strong open source tradition, which is a major priority for us in the decentralization space. In addition, JavaScript is the only language included in all browsers by default. Once you write a function, you can use it everywhere you need it on a node, in browsers, in command-line clients, or on auxiliary servers. This enables a greater level of efficiency in writing code, and greater consistency across projects. JAXenter: Were there other languages that you took into consideration before you decided to use JavaScript? Will Clark: This decision was taken long before I joined the team, and even before Lisk was born, given that Lisk forked its codebase from the preceding Crypti project. However, most of the benefits of this widely popular language all applied back then, and I Continue reading >>

How To Use Bitcoin Blockchain Be Useful To Authenticate Documents?

How To Use Bitcoin Blockchain Be Useful To Authenticate Documents?

have read a little about blockchains and found there is lot of blockchain npm libraries available. How can I take benefit of the bitcoin blockchain to authenticate documents : to obtain a proof a document has not been alterated ot changed. Any clues, suggestions, ideas and remarks are welcome. What do you mean "a document has not been altered or changed"? What's the difference between altering or changing a document and just having two different documents? Do you want to prove that a particular document is the documented someone signed or agreed to? Do you want to prove that a particular documented existed at a particular time? It's not clear what you're actually trying to do. David Schwartz Jul 6 '17 at 3:23 I'd suggest taking a look at chainpoint.org (Full disclosure, I'm the VP Engineering at Tierion, the creators of the Chainpoint open standard). Chainpoint currently uses the Tierion HashAPI, and you can submit hashes to the API for free. We'll provide you with a proof that you can store alongside your original document. We have a Javascript library you can use to access the HashAPI. We are getting ready to release a brand new v3 version of Chainpoint that has some great new features that we've announced (and some we haven't). Chainpoint v3 will be fully open source (clients and server), and free to use. I think you'll find it solves your needs quite nicely and we'd love your feedback. You can make a transaction with the hash (of the document) as a comment. That would proof that the file existed at that time. It doesn't however magically proof that a document hasn't been changed. Once you get the document, you can store the hash on the blockchain, then to check if it hasn't been changed, you can retrieve the hash and check if the current version of the file still h Continue reading >>

Learn & Build A Javascript Blockchain Part1

Learn & Build A Javascript Blockchain Part1

Learn & Build a Javascript Blockchain Part1 The best way to understand blockchain is to buildone In this Part 1 of the Javascript Blockchain Series, we will cover the block object and blockchain object and discuss its structure and implications. Im a firm believer in the idea that the best way to learn a technology is to build it. Naturally, my interest in blockchain technology has led me to try to build a blockchain of my own. As a fellow blockchain enthusiast, I will walk you through the steps of building a basic blockchain with a built-in proof of work system. Along the way, I will discuss the implications of the different features. What do you need: the latest version of Node.js (Im using v8.7.0) and npm (Node Package Manager) (Im using v5.6.0) Who is this for: anyone who is interested in learning about blockchain and has some basic understanding of Javascript Where is the repo: the code can be found here . Create a folder called js-blockchain and create a file called main.js In this guide, we will be using one single file so you can always refer to the source code if you encounter any problems. Blockchains are built through a combination of linked lists and merkle trees . The linked list structure allows for the chain to continually build on top of itself and is where the name blockchain derives from. A blockchain is literally a chain of blocks linked to one another through the linked list structure. One thing to note however, is that instead of holding a traditional pointer to refer to the previous block, it uses the hash of the previous block to refer to it. If you are not familiar with what a hash is, here is a primer . Hashes are simply deterministic functions that create specific outputs for each input, and they are usually irreversible meaning it is extremel Continue reading >>

Nodejs Blockchain Implementation: Brewchain: Chain+websockets+http Server

Nodejs Blockchain Implementation: Brewchain: Chain+websockets+http Server

DB Dev Blog - Javascript, NodeJS, React, Blockchain NodeJS blockchain implementation: BrewChain: Chain+WebSockets+HTTP Server I am going to create BrewChain. A verifiable chain of which member of the team made a brew and when. Protecting the history of events from any swindlers who may attempt to claim they have made more brews than they actually did. Our application will consist of the following: A Node which will run on team members machines, listening for new blocks broadcast and also broadcasting new blocks and updating the chain. An HTTP server and web interface for interacting with brew activities, the log and other data Blockchain is essentially a linked list in which each item contains a hash of the previous item. The fundamental element in this chain is the block. Each block contains data, and a hash of the previous block. This hashed pointer maintains the integrity of the data and makes the list immutable. To start with we need to determine the essential elements of our block. data - whatever we wish to store in the block hash - (a hash of the timestamp,index,data and previous hash) previous hash - the hash of the previous block const createBlock = (lastBlock, data) =>{ myBrew.addToChain(myBrew.createBlock('The 2nd block')); (The code in this post is in somewhat rough form while I workout exactly how it is going to work) This will setup our chain object, creating a genesis block and adding it to the chain. Our Brewchain contains the ability to create new blocks, add new blocks to our chain and also check the validity of a block. The test code at the end adds two blocks and then outputs the chain to check that the blocks are successfully being created. Well now begin building our P2P brewNode server.. Each BrewNode server will have a chain, a web socket server Continue reading >>

Access The Power Of Blockchain | Lisk

Access The Power Of Blockchain | Lisk

Lisk makes it easy for developers to build and deploy blockchain applications in JavaScript. Join the leading ecosystem for world-changing dapps. What can you build with Lisk? Get inspired with a selection of use cases. Lisk's decentralized network allows you to exchange value quicker and more economical than before. Build an internet of value. True scarcity and new possibilities for ownership revolutionize how digital content can be monetized. Blockchain transactions on Lisk provide insights into systems that previously lacked information, were obscured or unavailable. Military-level cryptography and distributed databases make Lisk a highly-secure solution for permission management and storage. Lisk's decentralized network is always online and eliminates the possibility for data loss. Data stored with Lisk is permanent and cannot be changed. Live data and archives finally have a secure digital home. Lisk's decentralized network allows you to exchange value quicker and more economical than before. Send value around the world in seconds and with much lower fees. Predict plot twists on Game of Thrones with people around the world using crowdsourced data. Build an internet of value. True scarcity and new possibilities for ownership revolutionize how digital content can be monetized. Trade rare items directly with other gamers. Those who create, curate and share content can finally be fairly rewarded for their contributions. Blockchain transactions on Lisk provide insights into systems that previously lacked information, were obscured or unavailable. Know precisely where your seafood came from, what it contains and how it got to you. Charity organizations can offer tracking for you to see exactly how your donation is being put to use. Military-level cryptography and distri Continue reading >>

Github - Ltearno/blockchain-js: A Generic And Simple Blockchain Distributed Consensus Implementation In Typescript

Github - Ltearno/blockchain-js: A Generic And Simple Blockchain Distributed Consensus Implementation In Typescript

A generic and simple blockchain distributed consensus implementation in typescript A simple typescript implementation of a Bitcoin-like distributed blockchain consensus algortihm. The aim is to have a working code base to make demoes and experiments with it. It has a node with many of the bitcoin concepts implemented, and some more (branches, merches, and so on). The code woks both on server (NodeJS) and client (browser) environments so it is fit for doing demoes. A demo application is available at . It is a chat (web) application using the underlying blockchain asthe data storage. This is perfect for showing simple code on how the bitcoin works, so this can be used as a support for demoes. This program maintains a distributed database accross active nodes, interconnected by the network. Since this is written in typescript, blockchain nodes can either run on NodeJS or in the browser. Traditionnal blockchain implemented concepts : proof of work (proof of stake can also be implementation as well as other algorithms, Concepts not in Bitcoin (as far as I know) branches : like with git, the blockchain structure supports branches. There is a master branchcalled master, then any branch can be built on it ! Continue reading >>

Is Javascript Enough To Work On Cryptocurrency And Blockchain?

Is Javascript Enough To Work On Cryptocurrency And Blockchain?

Answered Nov 17, 2015 Author has 712 answers and 779k answer views Javascript and Node.js are enough to build programs that interact with cryptocurrency APIs in real time. If you want to build your own cryptocurrency platform from scratch then C++ (Bitcoin), Go (Ethereum), Java (Nxt), etc might be better. 1.4k Views View Upvoters Answer requested by Answered Dec 1, 2017 Author has 98 answers and 44k answer views I can answer for Ethereum blockchain. In Ethereum, Web3 is a JavaScript framework to do transactions on the Blockchain. Apart from that, there is a programming language called Solidity to write smart contracts. Contracts are nothing but codified transactions on the blockchain. And for managing contracts as well as writing tests, Truffle NPM package is useful. For more info on Ethereum for JavaScript developers, please check Blockchain and Ethereum for JavaScript and React developers - Vijay T Yes it is! As a matter of fact, there is a powerfull cryptocurrency dApp platform running entirely in javascript - ShiftNRG When you look at the shift core, you can see that it is written in javascript. Also, their flagship IPFS decentralized application platform (Phantom) is made in javascript. And you can implement their shift-js library to make a API calls. You can find more info in provided links (Github repo, Landing page and Market cap info - Shift is one of the top 10 crypto for invest in 2018) Continue reading >>

Creating An App On Blockchain Technology Using Javascript

Creating An App On Blockchain Technology Using Javascript

Creating an app on Blockchain technology using JavaScript Blockchain technology is difficult, but with new JavaScript APIs Lisky hopes to make decentralization easier to program for developers. Creating an app on Blockchain technology using JavaScript As Blockchain technology comes into its own, it is becoming increasingly important for software developers and programmers to acquaint themselves with the benefits which blockchain can provide the architects and users of digital platforms and applications. Lisk is an application platform whose Software Development Kit allows users to code in JavaScript to build Blockchain applications, without needing to beBlockchainliterate. Fully customizable, apps built on Lisk can take any form, from new social media networks, games, and online stores to financial or accounting applications. In simplifying the creation of blockchain applications, Lisk is democratizing blockchain, extending the technologys benefits to all - even those with just rudimental programming experience. We sat down with Will Clark, Full Stack Lead at Lisky, to learn more about how developing blockchain-enabled applications through blockchain APIs is becoming easier. ADM: From a developers standpoint how has Blockchain technology changed the approach of creating platforms? Clark: Traditional platforms require a central authority to facilitate user interactions, whether it is a messaging platform (Twitter), a marketplace (eBay), or whatever. That hands a lot of control and responsibility to the central authority, because they essentially own the data. They are responsible for handling it securely, but they also have the power to modify or censor that data as they see fit. Building a platform on top of a blockchain removes the need for a central authority, and th Continue reading >>

How To Code A Bitcoin Like Blockchain In Javascript

How To Code A Bitcoin Like Blockchain In Javascript

This is a guest post by Michiel Mulders on How To Code a Bitcoin-like Blockchain In JavaScript The basic concept of a blockchain is quite simple: a distributed database that maintains a continuously growing list of ordered records. Add to this mining, mining rewards and blocks containing transactions. I think you get the general idea of a blockchain, right? There is nothing better than coding a blockchain yourself to fully grasp the inner workings of a blockchain. This tutorial will explain you to build a blockchain which returns mining rewards. The full code can be found here . Project Setup:How To Code a Bitcoin-like Blockchain In JavaScript As we like simplicity, we will only use three different files: app.js: contains the Express API for interacting with our blockchain. blockchain.js: contains the classes for constructing our blockchain, blocks, and transactions. package.json : contains our installed npm packages. The most important package we will use is crypto-js . This package contains crypto standards that can be used in JavaScript, like calculating our hash. In my opinion, a hash is the glue between two blocks. A lot of other packages can be found in this package.json file, mainly for compiling JavaScript ES7. Lets take a look at the different classes. A block consists of several properties. First, we pass a timestamp to indicate the moment the block got created. Next parameter is an array of transactions ready to be mined. At last, we define a field that contains the link to the previous block using a hash. This field is optional as the genesis block doesnt have a predecessor. class Block { constructor(timestamp, transactions, previousHash = '') { this.previousHash = previousHash; this.timestamp = timestamp; this.transactions = transactions; this.hash = this. Continue reading >>

Lotion - Smooth, Easy Blockchain Apps In Javascript

Lotion - Smooth, Easy Blockchain Apps In Javascript

Smooth, easy blockchain apps. Powered by Tendermint consensus. Lotion is a new way to create blockchain apps in JavaScript, which aims to make writing new blockchains fast and fun. It builds on top of Tendermint using the ABCI protocol. Lotion lets you write secure, scalable applications that can easily interoperate with other blockchains on the Cosmos Network using IBC . Lotion itself is a tiny framework; its true power comes from the network of small, focused modules built upon it. Adding a fully-featured cryptocurrency to your blockchain, for example, takes only a few lines of code . Note: the security of this code has not yet been evaluated. If you expect your app to secure real value, please use Cosmos SDK instead. A lotion application is usually a single function of signature (state, tx) which mutates your blockchain's state in response to a transaction. All of your application state is contained within a single JavaScript object. As a developer, all you need to do is design your application's initial state, then write the function to compute the next state when a transaction happens. Here's a minimal hello world example which simply counts the number of transactions that have occurred so far: let app = require('lotion')({ initialState: { count: 0 }})app.use((state, tx) => { state.count++})app.listen(3000) This will start the lotion application http server on port 3000, which you can use to query the state of the blockchain and create new transactions. The goal of a blockchain is to represent a single state being concurrently edited. In order to avoid conflicts between concurrent edits, it represents the state as a ledger: a series of transformations applied to an initial state. The blockchain must allow all connected nodes to agree about which transformations ar Continue reading >>

Create Your First Blockchain With Javascript

Create Your First Blockchain With Javascript

Create Your First Blockchain with JavaScript This is part of our series of tech talks given by our current immersive students. This talk will be held in English and Japanese. Blockchain is everywhere. The technology came to popularity through its powering of Bitcoin, which was invented in 2008. Now, it's the talk of the world and its areas of application are increasing past cryptocurrencies. The technology is actually a simple concept, though things can quickly get more complicated. So in this work shop, we will understand how this technology works by creating a simple blockchain using JavaScript. Ryuta Udo is a software engineer. After getting a Bachelor's in mechanical engineering, he moved to the Philippines to work for an e-learning company in marketing. He later moved into QA at the same company and became attracted to programming through his experience of working with engineers. After he worked for an advertising agency, he quit and is currently a student at Code Chrysalis. Continue reading >>

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