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Blockchain implementation in JS by @ssaurel
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class Blockchain { | |
constructor(difficulty) { | |
this.difficulty = difficulty; | |
this.blocks = []; | |
// Add Genesis Block | |
var genesisBlock = new Block(0, null, Date.now(), "Genesis block"); | |
genesisBlock.mineBlock(this.difficulty); | |
this.blocks.push(genesisBlock); | |
} | |
} | |
Blockchain.prototype.newBlock = function (data) { | |
var latestBlock = this.blocks[this.blocks.length - 1]; | |
return new Block(latestBlock.index + 1, latestBlock.hash, | |
Date.now(), data); | |
} | |
Blockchain.prototype.addBlock = function(block) { | |
block.mineBlock(this.difficulty); | |
this.blocks.push(block); | |
} | |
Blockchain.prototype.isFirstBlockValid = function() { | |
var firstBlock = this.blocks[0]; | |
if (firstBlock.index != 0) | |
return false; | |
if (firstBlock.previousHash != null) | |
return false; | |
if (firstBlock.hash == null || | |
calculateHash(firstBlock) != firstBlock.hash) | |
return false; | |
return true; | |
} | |
Blockchain.prototype.isValidBlock = function (block, previousBlock) { | |
if (previousBlock.index + 1 != block.index) | |
return false; | |
if (block.previousHash == null || | |
block.previousHash != previousBlock.hash) | |
return false; | |
if (block.hash == null || | |
calculateHash(block) != block.hash) | |
return false; | |
return true; | |
} | |
Blockchain.prototype.isBlockchainValid = function() { | |
if (!this.isFirstBlockValid()) | |
return false; | |
for (var i = 1; i < this.blocks.length; i++) { | |
var block = this.blocks[i]; | |
var previousBlock = this.blocks[i - 1]; | |
if (!this.isValidBlock(block, previousBlock)) | |
return false; | |
} | |
return true; | |
} | |
Blockchain.prototype.display = function() { | |
for (var i = 0; i < this.blocks.length; i++) { | |
var block = this.blocks[i]; | |
var str = "Block #" + block.index + " [" + | |
"previousHash: " + block.previousHash + ", " + | |
"timestamp: " + block.timestamp + ", " + | |
"data: " + block.data + ", " + | |
"hash: " + block.hash + "]"; | |
console.log(str); | |
} | |
} |
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