尝试设置前端时收到以下语法错误

Question

语法错误：在类构造函数（7：4）之外的super（）

我正在尝试为以太坊d-app构建React前端，但目前收到此错误，

任何帮助都会很棒！

谢谢。

class App extends Component {
 contructor(props) {

super(props);
}

const MyContract = window.web3.eth.contract 
([{var reactexampleContract = web3.eth.contract([{"constant":false,"inputs":[],"name":"kill","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"getSecret","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"youAwesome","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"payable":false,"stateMutability":"nonpayable","type":"fallback"}]);

this.state = {
  ContractInstance: MyContract.at ('0x77d914f8121dd1a15862e939546d969b2ddd3ee7')
}
this.querySecret = this.querySecret.bind (this);
 }

 querySecret () {
const { getSecret } = this.state.ContractInstance;

getSecret ((err, secret) => {
  if (err) console.error ('An error occured:::::', err);
  console.log ('This is our contracts secret', secret);
})