Unable to connect to web3 object using typescript and ethereum

Embarking on a fresh project with Angular 2 and TypeScript, I kicked things off by using the command:

ng new myProject

Next, I integrated web3 (for Ethereum) into the project through:

npm install web3

To ensure proper integration, I included the following in the head of index.html:

<script src="node_modules/web3/dist/web3.min.js"></script>

The path appeared to be correct as there were no errors (changing even one character triggered an error). Despite referring to the documentation at https://www.npmjs.com/package/web3, which suggested utilizing the web3 object directly from the global namespace like so: console.log(web3); I encountered an issue - web3 was not defined. How can I access this object? Please note that in the background, I initiated geth --testnet.

angulartypescriptethereum

Answer №1

Before using it, make sure to instantiate the web3 object initially. I tried it out with JavaScript:

var web3 = new Web3();
window.console.log(web3);
> Object { _requestManager: Object, currentProvider: undefined, eth: 
    Object, db: Object, shh: Object, net: Object, personal: Object, bzz: 
    Object, settings: Object, version: Object, 2 more… }

I'm not familiar with TypeScript, but the concept remains the same. The web3js library is there to assist you, and you must start by initializing it. This step is essentially mentioned first on the documentation page that's linked.

Answer №2

After much troubleshooting, I finally managed to come up with a solution to the problem at hand. However, there is an issue that arises half of the time during the transpilation process.

private acquireWeb3Provider(): Web3 {
if (typeof window.web3 !== 'undefined') {
  return new Web3(window.web3.currentProvider);
} else {
  this.web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:8545'));
  return this.web3;
}}

Additionally, within the constructor:

constructor() {
    this.label = 'Web3 Service';
    console.log(`${this.label}: initialized...`);
    this.web3 = this.acquireWeb3Provider();
  }

Answer №3

To access the object from the Window object, use the following method:

var ethereum: any = window["ethereum"];
var Ethereum: any = window["Ethereum"];
var ethereumInstance = new Ethereum(ethereum.currentProvider);
this.smartContract = ethereum.eth.contract(this.smartContractAbi).at(this.smartContractAddress);

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