Web3未连线

Question

I made a new project with truffle unbox react and assuming I deployed the dapp directly to Rinkeby with Infura I'm having a problem interacting with web3 in my app.js

I have a web3 file in my src folder here is its content

import Web3 from 'web3';

let web3 = new Promise(function(resolve, reject) {

window.addEventListener('load', function() {
 var results
 var web3 = window.web3

if (typeof web3 !== 'undefined') {
  web3 = new Web3(web3.currentProvider)

  results = {
    web3: web3
  }
  console.log(web3);
  console.log('Injected web3 detected.');

  resolve(results)
} else {
  var provider = new Web3.providers.HttpProvider('http://127.0.0.1:9545')

  web3 = new Web3(provider)

  results = {
    web3: web3
  }

  console.log('No web3 instance injected, using Local web3.');

  resolve(results)
  }
 })  
})

 export default web3

I then import that file to my app.js

import web3 from './web3';

And i just call in a JSX paragraph tag

  <p>  web3.utils.fromWei(this.state.balance, 'ether')  </p>

The error I get in my console log is as follows: "Uncaught TypeError: Cannot read property 'fromWei' of undefined"

I'm operating under the (possibly incorrect) assumption that web3 was downloaded when I ran the truffle unbox react command so no need to install it with npm.

Any ideas where I'm going wrong?

Thanks!

Answer 1

That's an async call you have to await it. await web3.utils.fromWei(this.state.balance, 'ether') should do.