General interviewing approach

STAR pattern:

• situation (how difficult was the task? what was the exact sitiuation? any impediments?)
• task (who gave the task? who assisted/helped/collaborated? what was the goal?)
• action (what exactly did you do? how? detail the steps you took!)
• result (can you detail the achieved result? was it good? what relevance did it have?)

In case there is little work experience in the CV we ask critical incident questions such as:

• Imagine the following situation: … How do you go about solving a, b, c …?

General questions:

• How do you organize your day?
• Give an example where you came up with a novel/original solution for an existing problem!
• Tell me about the most complex concept you've written thus far!
• Name three instances when you praised co-workers? Name three instances when co-workers praised you?
• In what areas have you developed the most in the last years?
• What is loose coupling?
• What is the "web"? What are web technologies? Name important stakeholders and institutions!

Frontend interview questions

JS/TS

• What is truthiness and falsiness in JS?
• Why use the === operator over the == operator?
• What is the difference between null, undefined?
• What is the difference between Object.create(null) and {}?
• What is a promise?
• Of what type is somePromise.then(someFn)?
• How to implement a promise yourself? (plain JS, no library, no new Promise() no async)
• When would one want to use var, when to use let, when to use const?
• What is rxjs?
• What is decorator?
• Why TypeScript?
• What are generics in TypeScript?
• How to move from a JS codebase to a TS codebase?
• How to test JS/TS code?

JS fun questions

• What is the shortest valid JS code?
• Why is there ECMAScript? Where did JavaScript come from?
• Name some JS runtimes? Elaborate!
• How to separate code in JS?
• What are callbacks? When to use them? What are some drawbacks to callbacks?

Unit testing

• How to unit test JS/TS code?
• Explain the test pyramid?
• What are some drawbacks to TDD?
• What is a mock, a stub, a spy, a test double?
• Name some of the types of libraries one might use in unit testing!

Design patterns

• What is functional programming?
• What is a factory?
• Name some design patterns!

Angular

• What is Angular?
• What is a component?
• What are the basic elements of an Angular app?
• Name common design patterns in an Angular app!
• How to approach routing?
• Explain template-driven and reactive (dynamic) forms!
• Name some common approaches to state management!
• How do you unit test in Angular?

CSS

• What is grid, what is flexbox?
• What are container queries?
• How to test CSS?

CSS fun questions

• Is CSS a programming language?
• How to prevent a CSS codebase from degenerating?

Tricky questions

Is Math.random a pure function? Elaborate!

Is myRandom a pure function? Elaborate!

function myRandom(numbers: Number[], pickRandomValueFn: (numbers: Number[]) => Number): Number {
    return pickRandomValueFn(numbers);
}

Example tasks

• What would you do, if you were tasked with writing unit tests for the + operator?
• Simple unit test https://stackblitz.com/edit/node-1plthi?file=test.js,trim-response.js