What I learned on this mini-project.

In this case, fetch is used to retrieve data from a url leading to a JSON data source.

fetch(endpoint).then(blob => blob.json());

This will return a promise, that can then be resolved to retrieve the data via json(), the following code will add the data to an array

fetch(endpoint).then(blob => blob.json()).then(data => cities.push(...data));

Note Use of the ... spread operator to push each data object into the array instead of it entirely (which would push the entire data source at index 0)

In order to use a variable as your matched string, you need to create a RegExp.

const regex = new RegExp(wordToMatch, 'gi');

This can then be used in match() methods for example

return place.city.match(regex);