CODEWITHSUNDEEP
javascriptethereumweb3jsmetamask
Alex Poloz
Alex Poloz

Reputation: 486

Undefined window.web3

When I try to invoke an Ethereum smart contract via web3js and MetaMask, I encounter the problem with getting window.web3. The message says that the value is undefined.

<script src="jquery.min.js"></script>
<script src="web3.min.js"></script>

<script type="text/javascript">

window.addEventListener('load',
function() {
    $("#loader").hide();

 	console.log('!');
	web3 = window.web3;
	console.log(web3);

    // Checking if Web3 has been injected by the browser (Mist/MetaMask)
    if (typeof web3 !== 'undefined') {
        // Use Mist/MetaMask's provider
        web3 = new Web3(web3.currentProvider);
        window.web3 = new Web3(web3.currentProvider);

    	console.log(web3.currentProvider);

        if (web3.currentProvider.isMetaMask === true) {

            startApp();
        } else {

            $('#results').html('No web3? Please use google chrome and metamask plugin to enter this Dapp!');

        }
    }
});
...

Console:

!

undefined

Upvotes: 3

Views: 4097

Answers (1)

Akshay Raje
Akshay Raje

Reputation: 892

window.web3 is injected by MetaMask only when viewing a page with http or https protocol. So effectively there wont be a web3 object in window scope if you are running this code in a blank (about:blank) page or in a local file without running a local server (URL starting with file:///)

Upvotes: 11

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