Merge #344

344: Fix nested object being transfom into [object, object] in highlight r=bidoubiwa a=bidoubiwa

The body of _highlightedResult used to look like this:

![Capture d’écran 2021-03-25 à 14 42 51](https://user-images.githubusercontent.com/33010418/112482638-90364600-8d78-11eb-93f3-bdfff1f4563a.png)

The field should be transformed to String using `JSON.stringify` to keep all information. 

<img width="923" alt="Screenshot 2021-03-25 at 15 20 33" src="https://user-images.githubusercontent.com/33010418/112488467-d93cc900-8d7d-11eb-9bc2-b1d4e26299a8.png">
It looks like this with this fix. 



Co-authored-by: Charlotte Vermandel <[email protected]>

Author: bors[bot]

src/format.ts

@@ -6,18 +6,18 @@ function replaceHighlightTags(
   highlightPreTag?: string,
   highlightPostTag?: string
 ): string {
-  let newHighlightValue = value || ''
-  // If the value of the attribute is a string,
-  // the highlight is applied by MeiliSearch (<em> tags)
-  // and we replace the <em> by the expected tag for InstantSearch
+  // Value has to be a string to have highlight.
+  // Highlight is applied by MeiliSearch (<em> tags)
+  // We replace the <em> by the expected tag for InstantSearch
   highlightPreTag = highlightPreTag || '__ais-highlight__'
   highlightPostTag = highlightPostTag || '__/ais-highlight__'
   if (isString(value)) {
-    newHighlightValue = value
+    return value
       .replace(/<em>/g, highlightPreTag)
       .replace(/<\/em>/g, highlightPostTag)
   }
-  return newHighlightValue.toString()
+  // We JSON stringify to avoid loss of nested information
+  return JSON.stringify(value)
 }
 
 function createHighlighResult<T extends Record<string, any>>({