For some use cases, the difference can be a little more dramatic.

    fetch(allResourcesUrl).then(async response => {
      let allResources = await response.json();
      let pageResource = await (await fetch(allResources.page1.url)).json();

      // set up page with pageResource
    });

can be replaced with

    {
      let allResources = await (await fetch(allResourcesUrl)).json());
      let pageResource = await (await fetch(allResources.page1.url)).json();

      //set up page with pageResource
    }

Note use of a top-level block instead of a function context to hide local variables.