Blockchain dynamic material library

1. const SHA256 = require(crypto-js/SHA256);< br />class Block{
constructor(index,timestamp,data,previousHash='&# 39;)< br />{
this.index=index;< br />this.timestamp=timestamp;< br />this.data=data;< br />this.previousHash=previousHash;< br />$this.hash=this.calculateHash();< br />}

calculateHash(){
return SHA256(this,index+this.previousHash+this.timestamp+JSON.stringify(this.data)).tostring();< br />}
}
class blockchain{
constructor(){
this.chain=[this.createGenesisBlock()];<
}
/ / create a generated information block
creategenesis block() {
return new block (0, & quot; 01/01/2019",& quot; Genesis block", 0);
/ / the date is the user's data. In fact, it is the hash value obtained by adding several values together. Here, the information is encrypted and the picture is encrypted. Then the data is still stored in the database, but all the data are hash values. To get this data, you must know the hash value of the previous data block. Then, if the hacker needs to crack all the nodes, the hash value is decrypted, Then all the blocks from the first node to the last node can be decrypted to get the real data. So the security of data stored in the blockchain depends on whether the data is encrypted. If the plaintext is not encrypted, then it is not a blockchain
}
/ / get the last block
getlatesblock() {
return this.chain [this.chain. Length-1]
}
/ / create block
addblock (newblock) {
newblock. Previoushash = this. Getlatesblock(). Hash< br />newBlock.hash=newBlock.calculateHash();< br />this.chain.push(newBlock);< br />}
}

2. Blockchain is the biggest trend in the next decade
if you look at the problem with the thinking of 30 years ago, you will think that others are crazy, but in fact you are out of date
the concept of blockchain can be traced back to the end of 2008. In the forum, a mysterious personage named "Nakamoto Tsung" published a paper "bitcoin: a peer-to-peer e-cash system" and proposed the concept of blockchain for the first time
on January 3, 2009, the first block of the blockchain was born, which is called the "Founding block"
almost with the birth of blockchain technology, bitcoin became the first thing to play its role. In the following years, bitcoin graally swept the world. In 2017, its crazy market made blockchain technology known to all
the idea of blockchain first appeared in the famous bitcoin open source project. In the process of its birth and development, bitcoin project draws on the technical achievements from digital currency, cryptography, game theory, distributed system, cybernetics and other fields. It can be said that bitcoin project is good at all. As its core supporting structure, blockchain technology is a remarkable innovation achievement
blockchain is a distributed database system with different nodes, which is an open ledger system<
three characteristics of blockchain
compared with the traditional centralized scheme, blockchain technology mainly has the following three characteristics:
the core idea of blockchain is decentralization
in the blockchain system, the rights and obligations between any node are equal, and all nodes have the ability to vote with computing power, Thus, the result recognized by more than half of the nodes is guaranteed. Even under serious hacker attacks, as long as the number of nodes controlled by hackers does not exceed half of the total number of nodes in the world, the system can still operate normally and the data will not be tampered with
block chain's biggest subversive is the establishment of credit
the collective maintenance of blockchain can rece the cost
in the centralized network system, the maintenance and operation of the system depend on the operation and operation of platforms such as data center, and the cost cannot be omitted. Anyone can participate in the nodes of the blockchain. Each node can verify the correctness of the results of other nodes' records while participating in the records, which improves the maintenance efficiency and reces the cost
in a word, blockchain touches money, trust and power, which are the fundamental basis for human survival< Its development has gone through three stages
1. Brewing period: from 2009 to 2012, bitcoin and its instrial ecology are the main economic forms
2. Embryonic period: from 2012 to 2015, with bitcoin entering the public view, new wallet payment and remittance companies appeared, and blockchain economy spread to the financial field. The underlying technology of blockchain is constantly innovated. Blockchain technology is separated from bitcoin system
3. Development period: in 2016, we began to explore instry applications, and a large number of blockchain start-ups appeared. The popularity of ICO in 2017 has given blockchain unprecedented attention
"blockchain 2.0 era" is coming
the application service layer is the driving force for the sustainable development of blockchain, which is divided into three stages of application: 1.0, 2.0 and 3.0
programmable currency: blockchain 1.0 application
programmable currency is the digital currency represented by bitcoin, but it is not the legal tender of any country or region, and there is no government authority to provide guarantee for it
programmable Finance: blockchain 2.0 application& quot; Smart contract& quot; Using program algorithm to replace the concept of contract execution. This enables blockchain to expand from the original monetary system to the registration and transfer of equity, creditor's rights and property rights, the transaction and execution of securities and financial contracts, and even the financial fields of gambling and anti-counterfeiting
programmable Society: blockchain 3.0 application
blockchain is the core of value Internet, which can confirm, measure and store the property rights of information and bytes representing value in each Internet. It can not only record the transactions of the financial instry, but also record almost anything valuable that can be expressed in the form of code. Its application can be extended to any field with demand, and then to the whole society
at present, the application of blockchain has begun to surpass bitcoin (blockchain 1.0), enter the era of blockchain 1.5, and transition to the financial field (blockchain 2.0)
in the next 3-5 years, blockchain may go beyond the financial field and enter the field of social notarization and intelligence (blockchain 3.0), including identity authentication, notarization, arbitration, audit, domain name, logistics, medical care, mail, visa, voting and other fields. Its application scope will be expanded to the whole society, and blockchain technology is likely to become a new technology& quot; All things are connected& quot; It's the lowest level protocol
at present, blockchain technology has been recognized by the world, and its development has become an inevitable trend. Accompanied by more people's attention, "in the next 30 years, new technologies will be integrated into all aspects of traditional instries, and human society will turn upside down. No matter who you are, no matter where you are, all of us will be a part of this great change."
this is the current situation. Blockchain has given the post-90s an opportunity. However, if you want to control blockchain technology without being affected by negative factors, the most important thing is to have a clear understanding of it, whether it is regulators, researchers, speculators or bystanders
it's time to devote more energy to blockchain technology
in China, the average annual salary of blockchain positions has reached more than 300000, and that of some enterprises has reached more than 1 million. The monthly salary of blockchain instry graates in Beijing, Shanghai and other places has exceeded 20K! If the post-90s seize the bonus of the times, they may become the next Alibaba in the future! If you miss it, you may regret it for ten years.

3. I just know your question. Please look at the following answer:
blockchain is an important concept of bitcoin. It is essentially a decentralized database and serves as the underlying technology of bitcoin. Blockchain is a series of data blocks generated by cryptography. Each data block contains the information of a bitcoin network transaction, which is used to verify the validity of the information (anti-counterfeiting) and generate the next block
the information websites in the instry now include:
1. Dig chain network: dig chain network is a professional blockchain media information portal. Dig chain network gathers the big data of global blockchain trading institutions, takes technology as the core, creates dig chain index, dig chain flash, dig chain College and other core sectors, excavates the value of blockchain, and serves as a platform for blockchain entrepreneurs, entrepreneurs and experts Blockchain investors provide one-stop blockchain service system
2. Golden Finance: a well-known old station in the instry
3. Color cloud bit: it is also the old cloud in the instry

you can learn more about it yourself.

4. There are many in China, you can search blockchain network or something, a lot of them.

5. Chongqing jinwowo: as for how to build a rigorous database, the method of blockchain is to innovate the structure of the database, divide the data into different blocks, link each block to the back of the previous block through specific information, and present a complete set of data in sequence, which is also the source of the three words "blockchain".