Making an API call within visual class.

[slinfoot]

Is it possible to make an API call using fetch in a custom visual.

I have set the privallages to allow web access to the API url and when I run the following function it succesfully prints the data in the console.

private async getData() {
        try {
            const url: string = 'http://localhost:3000/api/routes'
            const response = await fetch(url)
            const data = await response.json();
            console.log(data);
            //return data;
        } catch (error) {
            console.log(error);
        }

    }

The thing im struggling with is saving the returned data to a variable to use to create my visual. 

When I try to return the data to a variable in the constructor or update methods the variable is undefined or promise pending.