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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.

CC BY-NC 4.0 · © 2026

← Costco

New Grad / Junior Frontend at Costco

FrontendNew Grad / JuniorOutcome unknown◆ Commonly asked· 2025

A junior frontend loop. Pragmatic questions — more real-world than pure puzzles.

The loop · 5 rounds

01

Round 01 · 1 question

Online Assessment

Timed online coding / aptitude screen, usually the first filter.

  • Group items by frequency and return the top K.
    New Grad / JuniorMedium◆ Commonly asked
    #hashmap#heap
    PracticeGeeksforGeeks↗Search↗
02

Round 02 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Daily temperatures.
    New Grad / JuniorMedium◆ Commonly asked
    #stack#monotonic-stack
    PracticeLeetCode↗GeeksforGeeks↗
  • Longest consecutive sequence.
    New Grad / JuniorMedium◆ Commonly asked
    #hashmap#array
    PracticeLeetCode↗GeeksforGeeks↗
  • Course Schedule II.
    New Grad / JuniorMedium◆ Commonly asked
    #graph#topo-sort
    PracticeLeetCode↗GeeksforGeeks↗
03

Round 03 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Build a virtualized chat window that loads older messages.
    New Grad / JuniorHard◆ Commonly asked
    #react#virtualization
    PracticeGeeksforGeeks↗Search↗
  • Build a kanban board with drag and drop.
    New Grad / JuniorHard◆ Commonly asked
    #react#dnd
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • How do you optimize a slow React app? (profiling → fixes)
    New Grad / JuniorHard◆ Commonly asked
    #react#perf
    PracticeGeeksforGeeks↗Search↗
  • What are Web Workers and when would you use one?
    New Grad / JuniorMedium◆ Commonly asked
    #browser#perf
    PracticeGeeksforGeeks↗Search↗
  • How do you implement dark mode without a flash?
    New Grad / JuniorMedium◆ Commonly asked
    #css#ssr
    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.
    New Grad / Junior◆ Commonly asked
    #conflict#star
  • Tell me about a time you had to say no to a stakeholder.
    New Grad / Junior◆ Commonly asked
    #influence#star

Practice each round across every company

  • Online Assessment
  • DSA / Coding
  • Machine Coding
  • Tech Deep-Dive
  • Behavioral / HR

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