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Interview questions from top companies, mapped to the exact round they show up in. Prep for what you will actually face.

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Online AssessmentDSA / CodingMachine CodingLow-Level Design

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The Loop aggregates publicly shared interview experiences and curated commonly-asked questions, each labeled with its source. Not affiliated with any company listed.

MIT · © 2026

← Block

Mid Frontend at Block

FrontendMidOutcome unknown◆ Commonly asked· 2024

A mid frontend loop. Fast-paced; expect follow-ups that push on depth.

The loop · 5 rounds

01

Round 01 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Valid anagram.
    MidEasy◆ Commonly asked
    #string#hashmap
    PracticeLeetCode↗GeeksforGeeks↗
  • Product of array except self.
    MidMedium◆ Commonly asked
    #array#prefix-sum
    PracticeLeetCode↗GeeksforGeeks↗
  • Contains duplicate.
    MidEasy◆ Commonly asked
    #array#hashmap
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Build a typeahead with in-flight request cancellation.
    MidMedium◆ Commonly asked
    #react#async
    PracticeGeeksforGeeks↗Search↗
  • Build a form builder that renders from a JSON schema.
    MidHard◆ Commonly asked
    #react#forms
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 1 question

Low-Level Design

Object-oriented / low-level design of a focused module.

  • Design a virtual DOM diffing model.
    MidHard◆ Commonly asked
    #oop#algorithms
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • Difference between controlled and uncontrolled inputs.
    MidEasy◆ Commonly asked
    #react#forms
    PracticeGeeksforGeeks↗Search↗
  • Explain the difference between == and === and coercion.
    MidEasy◆ Commonly asked
    #javascript
    PracticeGeeksforGeeks↗Search↗
  • How does the browser critical rendering path work?
    MidMedium◆ Commonly asked
    #browser#perf
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 2 questions

Behavioral / HR

Values, collaboration, and past-experience (STAR) questions.

  • Describe a conflict with your manager and the outcome.
    Mid◆ Commonly asked
    #conflict#star
  • A time you made a mistake in production — what happened next?
    Mid◆ Commonly asked
    #ownership#star

◆ This experience is composed from commonly reported questions for this role and level. Real, individually-shared interviews will be layered in over time.