Question

我有一个由express生成器生成的node.js应用程序。我想使用Metamask插件注入的web3对象，但是当我尝试console.log（process.web3）时，它是未定义的。当我在浏览器的开发者控制台中键入window.web3时，它会返回web3对象。

有人知道注入web3对象的时间以及快递应用程序中我可以分配类似

的内容

var web3 = process.web3;

Answer 1

您是否尝试使用web3.js服务器端（在Node.js内）或客户端（在浏览器中）？看起来你正在混合这两种情况。

当浏览器加载JS库时，客户端web3.js被初始化。通常，如果您使用$(document).ready()之类的内容，则可以访问它。

服务器端web3.js需要implicit initialization。

Answer 2

您是否尝试过以下操作？我使用它连接到由metamask注入的web3。

import { default as Web3} from 'web3';

...

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

    // Checking if Web3 has been injected by the browser (Mist/MetaMask)
    if (typeof web3 !== 'undefined') {
        console.warn("Using web3 detected from external source. If you find that your accounts don't appear or you have 0 MetaCoin, ensure you've configured that source properly. If using MetaMask, see the following link. Feel free to delete this warning. :) http://truffleframework.com/tutorials/truffle-and-metamask")
        // Use Mist/MetaMask's provider
        window.web3 = new Web3(web3.currentProvider);
    } else {
        console.warn("No web3 detected. Falling back to http://127.0.0.1:8545. You should remove this fallback when you deploy live, as it's inherently insecure. Consider switching to Metamask for development. More info here: http://truffleframework.com/tutorials/truffle-and-metamask");
        // fallback - use your fallback strategy (local node / hosted node + in-dapp id mgmt / fail)
        window.web3 = new Web3(new Web3.providers.HttpProvider("http://127.0.0.1:8545"));
    }
});

希望这有帮助

什么时候web3对象被注入网页？

2 个答案: