I want to make a http get request when clicking on a button.
And also want to see the json data / or converted as a string as output for example in an alert window.

```
// async function
          async fetchAsync () {
            // await response of fetch call
            let response = await fetch('https://api.0x.org/swap/v1/quote?sellToken=ETH&buyToken=DAI&sellAmount=1000000000000000000');
            // only proceed once promise is resolved
            let data = await response.json();
            // only proceed once second promise is resolved
            return JSON.stringify(data);
          }

buttonEvent(){
             alert(

            this.fetchAsync()
              .then(data => alert(data))
              .catch(reason => console.log(reason.message))

             );
          }

          render() {
                return (

                    <button onClick = {this.buttonEvent}>Close Position</button>
)
}
}

```

Above you can see the code of the button component.
When i click the button in the app i get the error "TypeError: Cannot read property 'fetchAsync' of undefined"

How can i display the values from the http request in my app?