Frontend Developer
Mobile app development questions
50 questions on Mobile app development for frontend developers, easiest first.
Easy 12
- Square thumbnails from mixed photoseasy
- Images that overflow on phoneseasy
- Following the system dark modeeasy
- Smaller image fileseasy
- Logging state right after setting iteasy
- Two siblings that share a valueeasy
- Changing the initial state propeasy
- Rendering a list of citieseasy
- Modern image formatseasy
- What srcset is foreasy
- Oversized product photoeasy
- Blurred image placeholdereasy
Medium 27
- Multiple setState callsmedium
- Serving AVIF with a fallbackmedium
- Images that push content downmedium
- Loading the hero image soonermedium
- CSS variables versus Sass variablesmedium
- Which image srcset downloadsmedium
- White scrollbars in dark modemedium
- A manual dark mode togglemedium
- A small gap below an imagemedium
- Changing an object in statemedium
- Adding to a list in statemedium
- Removing a row from statemedium
- Expensive initial statemedium
- Two counters that share statemedium
- Same key in two different listsmedium
- When to reach for useReducermedium
- A slow page from one hover statemedium
- Rendering 20,000 rowsmedium
- Filters lost on refreshmedium
- A list that stops updatingmedium
- Lazy loading every imagemedium
- Getting sizes rightmedium
- Small file, slow pagemedium
- Different crop for phonesmedium
- Encoding images on uploadmedium
- Heavy animated GIFmedium
- Icon font for 20 iconsmedium
Hard 11
- Batching inside a timeouthard
- Too many re-renders errorhard
- Resetting selection when items changehard
- Setting state to the same valuehard
- A list item made of two elementshard
- Old value after an awaithard
- Putting a function in useStatehard
- Loading and error both truehard
- One slow field in a big formhard
- Choosing an image CDN setuphard
- Picking the srcset candidatehard