Uncaught ReferenceError: Web3 is not defined Solidity

Question

I've been working with this project and I downloaded all dependencies and Web3 already but when I test my code it shows me this:

Uncaught ReferenceError: Web3 is not defined

in line 120.

This is my code:

<script>
if(typeof web3 !== 'undefined'){
    web3 = new Web3(web3.currentProvider); -this is where it errors
}else {
    web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545")); 
}

web3.eth.defaultAccount = web3.eth.accounts[0];

var SuffrageContract = web3.eth.contract('example');
var Suffrage = SuffrageContract.at('example');
console.log(Suffrage);

I have already tried several methods like declaring

web3 = required('web3');

but it is still not working.

Answer 1

I hope you are using web3 as browser module.

As in their documentation, you can add the CDN link using <script> tags as below,

<script src="https://cdn.jsdelivr.net/gh/ethereum/web3.js/dist/web3.min.js"></script>

Answer 2

Are you wrapping this code with a window.addEventListener('load',...) handler?

Read here: Web3 - Ethereum Browser Environment Check

Note that the environmental web3 check is wrapped in a window.addEventListener('load', ...) handler. This approach avoids race conditions with web3 injection timing.

window.addEventListener('load', function() {

  // Checking if Web3 has been injected by the browser (Mist/MetaMask)
  if (typeof web3 !== 'undefined') {
    // Use Mist/MetaMask's provider
    web3js = new Web3(web3.currentProvider);
  } else {
    console.log('No web3? You should consider trying MetaMask!')
    // fallback - use your fallback strategy (local node / hosted node + in-dapp id mgmt / fail)
    web3js = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
  }

  // Now you can start your app & access web3 freely:
  startApp()

})