在前端页⾯调⽤合约写⼊数据时不会⽴即返回结果,这时需要再调⽤获取数据的函数,使⽤起来⾮常不便,这时event就可以很好解决这样的问题。 合约代码:
声明event事件:
event Deposit(address indexed _from, bytes32 indexed _id, uint _value);
触发event事件:
emit Deposit(msg.sender, _id, msg.value);
pragma solidity >=0.6.0 <0.9.0;
contract Demo {
陶瓷压机uint256 demoIndex = 0;
ito粉event DemoIndexInc(uint256 indexed index);
function getDemoIndex() public view returns (uint256) {
return demoIndex;
}
function incDemoIndex() public {
demoIndex = demoIndex+1;
emit DemoIndexInc(demoIndex);
}
}
H5代码:
pe导电
母粒虚拟传真订阅event事件:
<script src="./dist/web3.min.js"></script>
<script type="text/javascript">
const addEventWatchTx = async () => {
var web3 = new Web3(ethereum)
var metaTxContract = h.Contract(MetaTxABI, contractAddr)
metaTxContract.events.DemoIndexInc({
扭力梁式半独立悬架filter:{},
fromBlock: 'latest'
}, function(error, event){})
.on('data', function(event){
console.log(event); // same results as the optional callback above
})
可视化智慧水务
.
on('changed', function(event){
console.log('emove event from local database');
})
.on('error', );
}
</script>