Comment by justsomeuser

Under "Everything is an Expression":

        items = (() => {
          const results = [];
          for (const item of items) {
            if (item.length) {
              results.push(item.toUpperCase());
            } else {
              results.push("<empty>");
            }
          }
          return results;
        })();

Seems like they are purposely making the JS version extra long. It could be:

        items = items.map(x => x.length > 0 ? x.toUpperCase() : `<empty>`)

Edit: Just realised the code on the right is the compiled code, not the "equivalent hand written JS".