使用元掩码时检测 web3 默认帐户的更好模式
[英]Better pattern to detect web3 default account when using metamask
问题描述
Context: I want to use blockies to render an identicon on the page, i get the defaultAccount from web3, for this, the user has to be logged on to metamask with a selected address from his wallet.
上下文：我想使用 blockies 在页面上呈现一个身份图标，我从 web3 获取 defaultAccount，为此，用户必须使用钱包中选择的地址登录到 metamask。
The problem: the web app seems to not detect the web3 object on the load event of the page, wchih is the recommended place to detect it.问题：web 应用程序似乎没有在页面的加载事件上检测到 web3 对象，建议在 wchih 进行检测。
The code: below is inspired from recommendations at:代码：下面的灵感来自以下建议：
https://github.com/MetaMask/metamask-plugin/issues/1158 https://github.com/MetaMask/metamask-plugin/issues/1158
https://github.com/MetaMask/faq/blob/master/DEVELOPERS.md#partly_sunny-web3---ethereum-browser-environment-check https://github.com/MetaMask/faq/blob/master/DEVELOPERS.md#partly_sunny-web3---ethereum-browser-environment-check
I keep having intermittent behaviour, sometimes web3 is there and sometimes it is not, the only solution I can think of is to have a timer, but that seems to me a bit too simplistic, I would prefer something more elegant.我一直有间歇性行为，有时 web3 存在，有时不存在，我能想到的唯一解决方案是有一个计时器，但这在我看来有点过于简单，我更喜欢更优雅的东西。
Question: Is there a better solution to detect the defaultAccount from web3 when the page loads?问题：是否有更好的解决方案来在页面加载时从 web3 中检测 defaultAccount？
function startApp() {
GenerateIdenticon();
}
window.addEventListener('load', function () {
// Checking if Web3 has been injected by the browser (Mist/MetaMask)
if (typeof web3 !== 'undefined') {
// Use Mist/MetaMask's provider
window.web3 = new Web3(web3.currentProvider);
if (web3.currentProvider.isMetaMask === true) {
if (typeof web3.eth.defaultAccount === 'undefined') {
document.body.innerHTML = '<body><h1>Oops! Your browser does not support Ethereum Ðapps.</h1></body>';
}
else {
startApp();
}
}
else {
alert('No web3? Please use google chrome and metamask plugin to enter this Dapp!', null, null);
// fallback - use your fallback strategy (local node / hosted node + in-dapp id mgmt / fail)
window.web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
}
2 个解决方案
解决方案1
4 2018-03-28 16:34:32
function _Connect(callback){
if(typeof web3 !== 'undefined') {
web3 = new Web3(window.web3.currentProvider);
web3.version.getNetwork((err, netId) => {
switch (netId) {
case "1":
callback('Switch Network', null);
break
case "2":
console.log('This is the deprecated Morden test network.');
callback('Switch Network', null);
break
case "3":
console.log('Connected to the ropsten test network.');
web3.eth.defaultAccount = web3.eth.accounts[0];
if(!web3.eth.defaultAccount){
console.log('Log into metamask');
_Connect(callback);
}else{
// Success
console.log(`Web3 ETH Account: ${web3.eth.defaultAccount}`);
callback(false, web3.eth.defaultAccount);
}
break
default:
console.log('This is an unknown network.');
callback('Switch Network', null);
}
});
} else {
console.log(`Failed: Web3 instance required, try using MetaMask.`);
callback('Install Metamask', null);
}
}
解决方案2
0 2017-08-07 18:11:58
There is a delay when Chrome inserts the MetaMask Web3 library so the timeout is necessary (1 second timeout should be enough). Chrome 插入 MetaMask Web3 库时存在延迟，因此需要超时（1 秒超时应该足够了）。
After the timeout, you check if the web3 global object exists and then read the default account.超时后，检查 web3 全局对象是否存在，然后读取默认帐户。
If it doesn't exist, then insert your own web3 object.如果它不存在，则插入您自己的 web3 对象。
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