问题描述
我正在使用以太坊区块链,但是我的问题是JavaScript(异步,等待功能)。
这里我的代码简化了:
在我的html中
App.addBlockChain(n.username,n.first,n.last,n.email).then(value => {
**//here I need the hash of my transaction**
}).catch(error => {
alert("Errore: " + error );
});
在我的App.js文件中
addBlockChain: async(u,n,c,e) => {
let hash;
const web3 = new Web3(App.web3Provider);
const signed = await web3.eth.accounts.signTransaction(options,account.privateKey);
const receipt = await web3.eth.sendSignedTransaction(signed.rawTransaction)
.on('transactionHash',function(hash_returned){
//I need this hash hash_returned as soon as possible in my html ***
hash= hash_returned;
})
.on('receipt',function(receipt){... })
.on('confirmation',function(confirmationNumber,receipt){ ... })
.on('error',console.error); // If a out of gas error,the second parameter is the receipt.;
return hash; //it is returned only when on('confirmation') is terminated
有关示例代码的任何帮助吗?
提前谢谢。
解决方法
欢迎来到神奇的异步世界...一种实现方法是:
const hash_returned = await App.addBlockChain(n.username,n.first,n.last,n.email);
并在您的App类中:
addBlockChain: async(u,n,c,e) => {
const web3 = new Web3(App.web3Provider);
const signed = await web3.eth.accounts.signTransaction(options,account.privateKey);
return new Promise(resolve => { // addBlockChain must return a Promise,so it can be "await"ed
web3.eth.sendSignedTransaction(signed.rawTransaction)
.on('transactionHash',function(hash_returned) {
resolve(hash_returned); // now that you have hash_returned,you can return it by resolving the Promise with it
})
// or more simply (equivalent) :
// .on('transactionHash',resolve)
})
}