mbernardini/interview-questions

Interview Questions

An ever expanding list of possible interview questions.

General Questions

JavaScript/TypeScript

• Explain the difference between const, let and var?
• What are some JavaScript primitive types?
• number, boolean
• What is a prototype? What is it used for?
• Describe how scope resolution in JavaScript works?
• Explain bind and why you would us it?
• What is a Promise?
• How do you handle errors with promise? How is an exception handled?
• Explain your understanding of async/await?
• What do all async functions return?
• What might be a situation where you'd use a promise over await?
• Parallel execution (Promise.all) or your target environment doesn't support async/await
• What is destructuring? When might you use it?
• Syntactic sugar around assignment that allows you directly assign a variable from an object or an array.
• let {a, b} = JSON.parse("..."); let [value1, value2] = Promise.all(...)
• What is a decorator? When might you use it?
• A way to change the behavior of a function/class without making changes to the function/class itself.
• Use cases: logging, security, validation
• What is the spread operator? When might you use it?
• ... aka spread operator allows an iterable to be expanded in place
• Useful for array concatenation/copying, extending objects/copying, calling function (replace apply)

JavaScript WebAPI

• JavaScript interacts with HTML on a webpage using what API?
• DOM
• In a web browser how do you retrieve data from a web server using JavaScript?
• The older XMLHttpRequest (XHR) api is an event based API for creating async requests.
• The newer fetch api is a promised based API that simplifies retrieving data
• WebSockets is also a possibility and is well suited for applications requiring two way communication

Web Architecture

• What frameworks have you used?
• What do like about framework X? What do you not like?
• If you had to choose a front end framework, which would you choose?
• If you had to choose a server framework, which would you choose?
• Are you familiar with OAuth? Can you explain at a high level how it works?
• Why would you choose to use WebSockets over HTTP or Server Side Events?
• Explain the same-origin policy. How do you get around same-origin policy limitations? Explain how CORS works.

Networking

• What are the two most common transport layer protocols built on top of internet protocol?
• Explain the difference between UDP and TCP? What are some benefits and drawbacks of each?
• What transport layer protocol does HTTP use? How about WebSockets? WebRTC?
  • TCP
  • TCP
  • SDP

Ops

• How have you managed things like passwords in your code?
• What tools have you used for secrets management?
• Have you heard of the 12 factor app?
• Can you explain your understanding of the 12 factors?

Functional

• Explain map. Explain flatMap
• Explain reduce

Project/time management

• How have you handled a project that you thought you could get done by a certain date but as the deadline approached, you realized you would be unable to complete it?
• How do you balance writing tests with a strict project deadline?

Exercises

Prefix searching

Suppose that you need to search a list of words to find all words that begin with a search term. Assume you are given the words in array.

E.g. Given an english dictionary, "sup" => ["superior", "superlative", "supine" ...]

Q1: Implement an naive solution

const dict = ["one", "two", "three", "four"];

function search(prefix) {
  const results = [];
  results.forEach(word => {
    if(word.startsWith(prefix)) {
      results.push(word);
    }
  });
  return results;
}

// or perhaps
const search = (prefix) => dict.filter(word => word.startsWith(prefix));

What is the runtime of your solution? (big O)

Example code is O(NM) where N is the number of characters in prefix and M is the length of the dictionary

Q2: What are some possible optimizations you might make to the above solution?

TODO: finish

Find the length of a Line String

TODO: implement

Triangle Counting

Given N nonparallel lines, implement a function that calculate the number of triangles produced by intersecting lines. Intersections points are infinitely small and therefore no three lines intersect at the same point.

TODO: solution