tsiege

ANNOUNCEMENT

I have moved this over to the Tech Interview Cheat Sheet Repo and has been expanded and even has code challenges you can run and practice against!






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mperham

I want to build a system which uses rules. These rules will change hourly (i.e. "this rule is effective from 2pm to 6pm"). The rules must support arbitrarily complex logic on just 2-3 pre-defined variables and result in a boolean:

item.a > 10 && item.b == 0 || item.category == FOOTWEAR

These rules will be executed hundreds of times per second so I can't afford the overhead of plain old eval. I want to reload the current effective ruleset from the database hourly, precompile each rule's logic string and execute it via the quickest method possible. It might look something like this:

class Rule

robmiller

#!/usr/bin/env ruby

def run
  ARGF.each_slice($options[:columns]) do |values|
    puts values.map(&:chomp).join($options[:separator])
  end
end

require "optparse"

SamSaffron

# speed up pluck

class ActiveRecord::Relation

  class RailsDateTimeDecoder < PG::SimpleDecoder
    def decode(string, tuple=nil, field=nil)
      if Rails.version >= "4.2.0"
        @caster ||= ActiveRecord::Type::DateTime.new
        @caster.type_cast_from_database(string)
      else

codesnik

module AROpts

  module Helpers
    def GT(val); AROpts::GT.new(val); end
    def LT(val); AROpts::LT.new(val); end
    def GTE(val); AROpts::GTE.new(val); end
    def LTE(val); AROpts::LTE.new(val); end
  end

  GenericOp = Struct.new(:expression)

joepie91

Not all random values are created equal - for security-related code, you need a specific kind of random value.

A summary of this article, if you don't want to read the entire thing:

• Don't use Math.random(). There are extremely few cases where Math.random() is the right answer. Don't use it, unless you've read this entire article, and determined that it's necessary for your case.
• Don't use crypto.getRandomBytes directly. While it's a CSPRNG, it's easy to bias the result when 'transforming' it, such that the output becomes more predictable.
• If you want to generate random tokens or API keys: Use uuid, specifically the uuid.v4() method. Avoid node-uuid - it's not the same package, and doesn't produce reliably secure random values.
• If you want to generate random numbers in a range: Use random-number-csprng.

You should seriously consider reading the entire article, though - it's

bvaughn

// This is an advanced example! It is not intended for use in application code.
// Libraries like Relay may make use of this technique to save some time on low-end mobile devices.
// Most components should just initiate async requests in componentDidMount.

class ExampleComponent extends React.Component {
  _hasUnmounted = false;

  state = {
    externalData: null,
  };

shrayasr

body {
    margin: 0 auto;
    width: 900px;
    font-family: Trebuchet MS;
    font-size: 16px;
    line-height: 23px;
    margin-top: 20px;
    background: #fff8ec;
}

vcarl

I bundled these up into groups and wrote some thoughts about why I ask them!

If these helped you, I'd love to hear about it!! I'm on twitter @vcarl_ or send me an email [email protected]

Onboarding and the workplace

https://blog.vcarl.com/interview-questions-onboarding-workplace/

• How long will it take to deploy my first change? To become productive? To understand the codebase?
• What kind of equipment will I be provided? Will the company pay/reimburse me if I want something specific?

geetotes

server {

        root /var/www/status.icu;
        index index.html;
        server_name status.icu;
        location / {
                try_files $uri $uri/ =500;
        }

        location ~ /200  {