search: Add keyboard navigation to results

After searching for a string, the user can navigate results by pressing up/down arrows.

Author: zsol

www/components/core/Search.tsx

@@ -41,6 +41,9 @@ const ItemLink = styled(Link)`
   display: block;
   padding: ${(props) => props.theme.spacing.xs};
   text-decoration: none;
+  &:focus {
+    background-color: ${(props) => props.theme.colors.input.hover};
+  }
 
   width: 100%;
 `;
@@ -93,21 +96,39 @@ export const Search = ({ descriptors }: SearchParams) => {
     }
   }, [searchTerm]);
 
+  function keyPressHandler(event: React.KeyboardEvent, index: number) {
+    if (event.key === "ArrowDown" && index + 1 < (results?.length ?? 0)) {
+      document.getElementById(`SearchResultItem_Link_${index+1}`)?.focus();
+      event.preventDefault();
+    } else if (event.key === "ArrowUp" && index >= 0) {
+      const target = document.getElementById(index === 0 ? "Search_Input" : `SearchResultItem_Link_${index-1}`);
+      target?.focus();
+      event.preventDefault();
+    }
+  }
+
   return (
     <SearchContainer>
       <input
+        id="Search_Input"
         onChange={(event) => {
           setSearchTerm(event.target.value);
         }}
         value={searchTerm}
+        onKeyDown={(event) => keyPressHandler(event, -1)}
       />
       {searchTerm && results && (
         <SearchResultContainer>
           {results.total === 0 && "No results found"}
           {results.total > 0 &&
             results.map((result: Result, ind: number) => (
               <SearchResultItem key={`${result.obj.name}_${ind}`}>
-                <ItemLink to={`${result.obj.url}`} onClick={(event) => setSearchTerm("")}>
+                <ItemLink
+                  id={`SearchResultItem_Link_${ind}`}
+                  to={`${result.obj.url}`}
+                  onClick={() => setSearchTerm("")}
+                  onKeyDown={(event) => keyPressHandler(event, ind)}
+                  >
                   <Match result={result} />
                 </ItemLink>
               </SearchResultItem>