Evan X. Merz

musician/technologist/human being

Sam Hyde Harris: Seeing the Unusual at Casa Romantica

I recently attended the exhibit Sam Hyde Harris: Seeing the Unusual at Casa Romantica in San Clemente, California. The exhibit was curated by Maurine St. Gaudens and Joseph Marsman and brought together around 60 pieces by Sam Hyde Harris in just two rooms on the lovely Casa Romantica estate.

Sam Hyde Harris is mostly remembered by collectors today as an active member of the California Art Club who produced hundreds of beautiful landscapes of California in the early 20th century and taught numerous students who went on to great careers. He was also a member of a group called the California Impressionists.

The focus of this exhibit was introducing a modern audience to the massive volume of commercial work he produced. This includes numerous posters for companies such as Union Pacific and the Santa Fe Railroad, as well as advertising pieces for local businesses and theater companies.

Union Pacific poster by Sam Hyde Harris

Here's the Curator's Statement from Maurine St. Gaudens.

Sam Hyde Harris, Seeing the Unusual explores the diverse oeuvre of this noted twentieth century California artist. Although widely known for the fine art compositions, few people realize the extent of Harris' commercial advertising work. Harris' designs shaped the consciousness of early to mid-twentieth century consumers and travelers. I really was quite surprised that so little attention had been paid to Harris the commercial artist. This exhibition explores this complex aspect of the artist's career.

My personal association with Sam Hyde Harris actually began more than thirty years ago when I was contacted by Harris' widow, Marion Dodge Harris, to catalogue the artist's estate. In the process I discovered examples of work the artist had created for a who's who of clients, not only in California, but across the western United States and nationally. It's the commercial work that today represents an historical record of product lines and services that were a part of everyday life from the 1920s - 1950s.

Art produced by Sam Hyde Harris for Gilmore Gasoline.

On a national level, Harris had a long and highly creative relationship with the railroad industry, specifically the Santa Fe, Southern Pacific, and Union Pacific rail lines. His iconic Art Deco themed Southern Pacific's New Daylight poster has become one of the most recognizable images of this art form and one that has become highly praised by railroad and design enthusiasts alike.

Unfortunately, over the years, as is common with many commercial artists, their work has gone unaccredited, and Harris is no exception. Although, with new research and recent descoveries, this oversight is now being corrected, and Harris' commercial designs are being recognized by a new generation of historians.

Harris' commercial work wasn't the only thing in the exhibition, though. There were plenty of paintings of the subjects for which he was most famous, including boats in harbor, and the Chavez Ravine before it was developed.

Paintings of boats by Sam Hyde Harris.

I spent an hour poring over every piece in the exhibit. Many of the pieces came from the collection of Charles N. Mauch, including several massive paintings that became his most famous posters. I particularly enjoyed seeing the different stages of the Taxco Mission poster produced for Southern Pacific. Through a sketch, a painting, and a print of the final poster, visitors could see the complete evolution of one of his commercial pieces.

I only recently became a fan and collector of work by Sam Hyde Harris, and I was glad to have the opportunity to see so much of his work in one place. I was also glad that this less well-known California artist was being brought to new audiences in the 21st century.

Sam Hyde Harris: Seeing the Unusual ran from November 19, 2021 through February 27, 2022.

Discovering artist Viola M. Allen

I recently purchased Emerging from the Shadows, Vol. I: A Survey of Women Artists Working in California, 1860-1960 and while reading it I discovered one particularly interesting artist named Viola M. Allen. Her facility with a palette knife seems almost miraculous, so of course I started searching the web for more of her work. Other than a few items available at auction, I haven't been able to find much information. So I wanted to share a couple quotes from the fabulous book by Maurine St. Gaudens.

Viola M. Allen was born on March 14, 1906, in Queens, New York, the daughter of Safarine D. Allen and Minnie (Eschman) Allen. According to her biographical artist's promotional card, she attended, in New York, the Pratt Institute and the National Academy of Design, where she studied under Charles Curran. Her card also indicates that she studied portrait painting with Moskowitz and Borgdonav and sculpture with Haffner and Monahan. A resident of Manhattan, New York, through the 1930s, by the latter part of the decade she had moved to Los Angeles, California; she remained a California resident until her death.

A painting by Viola M. Allen

A study of Viola's paintings shows that she was a palette knife painter. Her ability to create realistic compositions by applying oil paint to a canvas, or board, by the use of a flexible painter's palette knife rather than a brush is found in most of her work; it is a difficult technique and one not widely practiced. Palette knives vary in length and width, and each one has a different tip, enabling the artist to achieve a different type of stroke, with the oil painting usually being applied very thickly on the canvas or board. During her career Viola had a commercial art studio in Malibu for many years where she did illustration and advertising art. In California, she exhibited with the California Art Club, 1955-1967.

This was all I could find out about her, and I'm happy to share it on the internet, and hopefully bring a little more attention to an artist who clearly had a control over the palette knife that few have ever achieved.

Of course I had to see if I could find one of her works at a reasonable price, and ebay came to my aid once again. I was able to find this beautiful small landscape listed for a song and now it hangs over my desk next to Sam Hyde Harris and Quincy Tahoma.

A small, untitled landscape by Viola M. Allen

I don't think I've ever seen another artist wield a palette knife as fluently as she did, so I'll be on the lookout for more of her work. I hope that the internet can help preserve the legacy of a great artist who clearly deserves a re-evaluation.

Why to stick with Heroku, or make the switch

One question I hear a lot lately is when a company should stick with Heroku or switch to something else. In this article I'm going to lay out the pros and cons for Heroku, and compare it with the typical alternative, AWS.

Three reasons to stick with Heroku

Don't fall victim to thinking that "the grass is always greener on the other side." That hot new technology on AWS or Azure may look cool now, but Heroku offers a lot of great features that should fit the bill for many growing companies.

Heroku supports easy scaling with sticky sessions

Horizontally scaling any web application is hard. In a traditional web app, you must optimize your code so that it runs in parallel. You must deal with race conditions that arise when multiple servers are trying to interact with a shared resource such as a cache or a database. You must find a way to balance load across multiple servers while sharing state across all instances.

Session data is visitor-specific data that is stored on the server. If a visitors's session is stored on one server, but their request is routed to another server, then that server won't know about anything they've done in the current session. It may not know if they're logged in or not. It may not have the browsing filters that they've configured.

Session affinity, also known as sticky sessions, is one solution to the problem of sharing session across servers. With session affinity enabled, all of a visitor's requests will always be routed to the same instance. There are some drawbacks to session affinity, but the benefit of being able to scale horizontally before having to tackle some parallelization problems may outweigh the drawbacks in your use case.

Many services offer session affinity, but none are as easy to set up as Heroku. With literally two clicks you can enable session affinity and start scaling out. Don't let hype distract you from an approach that may reap benefits for your web property.

Heroku provides zero down time deploys and upgrades

One of the best features of Heroku is that their technology and support teams handle deploys and upgrades. They make it so that your dev team doesn't have to worry about keeping the servers up during deploys or running migrations during upgrades.

The preboot feature allows you to keep the old version of your app running during a deploy. This means that users will only ever be routed to a server that has booted up and is running your app, and that means that you aren't turning away customers in that 30 second window where the new version of your app is loading.

Heroku also supports seamless upgrades for the most popular add-ons, such as REDIS. When I switched my company from Heroku REDIS to AWS REDIS we were surprised that our site went down a few weeks after the switch. AWS may force upgrade your technology without providing a way to seamlessly switch to the new version. So AWS forces you to track each upcoming patch and ensure that your team is ready for the switch.

Heroku is cheaper than the alternative because anyone can use it

Heroku seems very expensive when the bills come due, but in my experience it's cheaper than the alternative. Heroku is so easy to use that anyone can use it. With a few clicks or commands a backend developer can enable sticky sessions. With a few clicks or commands they can enable preboot. With a few clicks or commands they can add REDIS or PostGreSQL or any of the many add-ons provided by Heroku.

To use all those different products on a less managed product, such as AWS or Azure, you must retain a dedicated DevOps specialist. These people have very specialized skills and are not cheap. In my experience, using Heroku saves the cost of around one expensive employee. So as long as your Heroku bill is less than the cost of one employee, it's probably the more affordable option.

Three reasons to switch

There are many good reasons to stick with Heroku, but it certainly has limits. Here are the reasons why I've moved services from Heroku to somewhere else in the past.

Heroku is dangerous because anyone can use it

When you're on Heroku, you may not need to hire dedicated staff to manage your web infrastructure. This is a significant cost savings, but it means that the DevOps tasks are going to be offloaded on your web programmers. So you must ensure that you hire the skills on your team to understand Heroku. Heroku may not be as complex as AWS, but it still requires a foundational understanding of how the web works, linux, and logging. If your programmers are exploring the features in Heroku without the requisite experience or training then they may make mistakes that harm your business.

Heroku offers fewer options for international support

Heroku lacks flexible support for internationalized websites. As it says in the regions documentation, each "Private Space exists in a single region, and all applications in the Private Space run in that region.". This may sound confusing, but it ultimately means that each project in Heroku can only run in one region. If you want to support another region, then it must be in a separate project and hosted at a separate domain or subdomain. So if you want to internationalize your website using subdirectories, which is advantageous because it inherits the existing search reputation of your domain, then you can't do that with geographically distributed servers on Heroku.

Heroku offers fewer vertical scaling options

Heroku dynos come in six different flavors as of this writing. If you need anything outside of those six options then you are out of luck. The beefiest dyno is the performance-l machine, which offers 14Gb of RAM. If you need more than that, then you need to switch to another platform. What if you're using very little memory, but you want to use many CPU cores? The only option is to pay for the most expensive dynos. This lack of flexibility means that if your web service is a pretty standard website or API, then Heroku probably won't serve your needs very well.

How to decide whether to stick with Heroku or to switch

In this article I've listed some reasons to stick with Heroku and some reasons to switch, but the final decision is largely dependent on your use case. If you are making a pretty standard website or API, then Heroku is probably fine even when horizontally scaling. There are three main scenarios where you should strongly consider switching to a more complex cloud hosting service.

  1. Your service need more flexible options for internationalization
  2. Your service doesn't match the requirements common to most web apps and APIs
  3. Your service is scaling exponentially

Evan's React Interview Cheat Sheet

In this article I'm going to list some of the things that are useful in React coding interviews, but are easily forgotten or overlooked. Most of the techniques here are useful for solving problems that often arise in coding interviews.

Table of contents

Imitating componentDidMount using React hooks

The useEffect hook is one of the more popular additions to the React hooks API. The problem with it is that it replaces a handful of critical lifecycle methods that were much easier to understand.

It's much easier to understand the meaning of "componentDidMount" than "useEffect({}, [])", especially when useEffect replaces componentDidMount, componentDidUpdate, and componentWillUnmount.

The most common use of the useEffect hook in interviews is to replace componentDidMount. The componentDidMount method is often used for loading whatever data is needed by the component. In fact, the reason it's called useEffect is because you are using a side effect.

The default behavior of useEffect is to run after ever render, but it can also be run conditionally using a second argument that triggers the effect when it changes.

In this example, we use the useEffect hook to load data from the omdb api.

  // fetch movies. Notice the use of async
  const fetchMovies = (newSearchTerm = searchTerm) => {
    // See http://www.omdbapi.com/
    fetch(`http://www.omdbapi.com/?apikey=${apikey}&s=${newSearchTerm}&page=${pageNumber}`).then(async (response) => {
      const responseJson = await response.json();

      // if this is a new search term, then replace the movies
      if(newSearchTerm != previousSearchTerm) {
      } else {
        // if the search term is the same, then append the new page to the end of movies
        setMovies([...movies, ...responseJson.Search]);
    }).catch((error) => {

  // imitate componentDidMount
  useEffect(fetchMovies, []);

Note that this syntax for using asynchronous code in useEffect is the suggested way to do so.

Using the previous state in the useState hook

The useState hook is probably the easiest and most natural hook, but it does obscure one common use case. For instance, do you know how to use the previous state in the useState hook?

It turns out that you can pass a function into the useState set method and that function can take the previous state as an argument.

Here's a simple counter example.

const [count, setCount] = useState({});
setCount(prevState => {
  return prevState + 1;

Using useRef to refer to an element

The useRef hook is used to store any mutable value across calls to the component render method. The most common use is to use it to access an element in the DOM.

Initialize the reference using the useRef hook.

// use useRef hook to keep track of a specific element
const movieContainerRef = useRef();

Then attach it to an element in the render return.

<div className={MovieListStyles.movieContainer} ref={movieContainerRef}>
  {movies && movies.length > 0 && 

Then you can use the .current property to access the current DOM element for that div, and attach listeners or do anything else you need to do with a div.

// set up a scroll handler
useEffect(() => {
  const handleScroll = debounce(() => {
    const scrollTop = movieContainerRef.current.scrollTop;
    const scrollHeight = movieContainerRef.current.scrollHeight;
    // do something with the scrolling properties here...
  }, 150);

  // add the handler to the movie container
  movieContainerRef.current.addEventListener("scroll", handleScroll, { passive: true });

  // remove the handler from the movie container
  return () => movieContainerRef.current.removeEventListener("scroll", handleScroll);
}, []);

Custom usePrevious hook to simplify a common useRef use case

The useRef hook can be used to store any mutable value. So it's a great choice when you want to look at the previous value in a state variable. Unfortunately, the logic to do so is somewhat tortuous and can get repetitive. I prefer to use a custom usePrevious hook from usehooks.com.

import {useEffect, useRef} from 'react';

// See https://usehooks.com/usePrevious/
function usePrevious(value) {
  // The ref object is a generic container whose current property is mutable ...
  // ... and can hold any value, similar to an instance property on a class
  const ref = useRef();
  // Store current value in ref
  useEffect(() => {
    ref.current = value;
  }, [value]); // Only re-run if value changes
  // Return previous value (happens before update in useEffect above)
  return ref.current;

export default usePrevious;

Using it is as simple as one extra line when setting up a functional component.

// use the useState hook to store the search term
const [searchTerm, setSearchTerm] = useState('orange');

// use custom usePrevious hook
const previousSearchTerm = usePrevious(searchTerm);

Vanilla js debounce method

Okay, this next one has nothing to do with React, except for the fact that it's a commonly needed helper method. Yes, I'm talking about "debounce". If you want to reduce the jittery quality of a user interface, but you still want to respond to actions by the user, then it's important to throttle the rate of events your code responds to. Debounce is the name of a method for doing this from the lodash library.

The debounce method waits a preset interval until after the last call to debounce to call a callback method. Effectively, it waits until it stops receiving events to call the callback. This is commonly needed when responding to scroll or mouse events.

The problem is that you don't want to install lodash in a coding interview just to use one method. So here's a vanilla javascript debounce method from Josh Comeau.

const debounce = (callback, wait) => {
  let timeoutId = null;
  return (...args) => {
    timeoutId = window.setTimeout(() => {
      callback.apply(null, args);
    }, wait);

export default debounce;

Here's an example of how to use it to update a movie list when a new search term is entered.

// handle text input
const handleSearchChange = debounce((event) => {
}, 150);

return (
  <div className={MovieListStyles.movieList}>
    <h2>Movie List</h2>
    <div className={MovieListStyles.searchTermContainer}>
        <input type="text" defaultValue={searchTerm} onChange={handleSearchChange} />
      {movies && movies.length > 0 && 

Use useContext to avoid prop-drilling

The last thing an interviewer wants to see during a React coding interview is prop drilling. Prop drilling occurs when you need to pass a piece of data from one parent component, through several intervening components, to a child component. Prop drilling results in a bunch of repeated code where we are piping a variable through many unrelated components.

To avoid prop drilling, you should use the useContext hook.

The useContext hook is a React implementation of the provider pattern. The provider pattern is a way of providing system wide access to some resource.

It takes three code changes to implement the useContext hook. You've got to call createContext in the parent component that will maintain the data. Then you've got to wrap your app with a special tag.

export const DataContext = React.createContext()

function App() {
  const data = { ... }

  return (
      <DataContext.Provider value={data}>
        <SideBar />
        <Content />

Then you've got to import the context in the child component, and call useContext to get the current value.

import DataContext from '../app.js';


const { data } = React.useContext(DataContext);

What has made you stumble in React interviews?

What are some other common ways to make mistakes in React coding interviews? Send me your biggest React coding headaches on Twitter @EvanXMerz.

How to measure the performance of a webpage

How to measure the performance of a webpage

Measuring the performance of a webpage is an extremely complex topic that could fill a book. In this article I'm going to introduce some of the commonly used tools for measuring web performance, and show you why you need to take multiple approaches to get a complete picture of the performance of any webpage.

Why measure webpage performance?

Why measure webpage performance? Performance is so critical to the modern web that this question seems almost comical. Here are just a few reasons why you should be measuring and monitoring webpage performance.

  1. User experience impacts Google search rankings via Core Web Vitals.
  2. Page load time correlates with conversion rate and inversely correlates with bounce rate.
  3. Pages must be performant to be accessible to the widest possible audience.

Four approaches to measuring performance

No single tool is going to give you a comprehensive perspective on webpage performance. You must combine multiple approaches to really understand how a page performs. You must look at multiple browsing patterns, multuple devices, multiple times of day, and multiple locations.

In this article, I'm going to talk about four different approaches to measuring the performance of a page and recommend some tools for each of them. You must use at least one from each category to get a complete picture of the performance of a webpage.

The four approaches I'm going to talk about are...

  1. One time assessments
  2. Live monitoring and alerts
  3. Full stack observability
  4. Subjective user tests

Why do we need multiple perspectives to measure performance?

People who are new to monitoring web performance often make mistakes when assessing web performance. They pull up a website on their phone, count off seconds in their head, then angrily email the developers complaining that the website takes 10 seconds to load.

The actual performance experienced by users of your website is an important perspective, but there are dozens of things that can impact the performance of a single page load. Maybe the page wasn't in the page cache. Maybe the site was in the middle of a deploy. Maybe hackers are attacking network infrastructure. Maybe local weather is impacting an ISP's network infrastructure.

You can't generalize from a single page load to the performance of that page. I've seen many people fall into this trap, from executives to marketing team members. It makes everyone look bad. The website looks bad because of the slow page load. The developers look bad because of the poor user experience. The person who called it out looks bad because it looks like they don't know what they are doing. The data analysts look bad because they aren't exposing visualizations of performance that other team members can use.

So read this article and fire up some of the tools before sending out that angry email.

Please note that the tools listed here are just the tools that I have found to be effective in my career. There are many other options that may be omitted simply because I've never used them.

One time assessments

One time assessments are the most commonly used tools. One time assessments can be run against a production webpage at any time to get a perspective of the performance at that moment. One thing that's nice about these tools is that they can be used effectively without paying anything.


  1. Easy to use
  2. Easy to quantify
  3. Fast
  4. Reliable
  5. Affordable


  1. May lack perspective over time
  2. Lacks perspective on actual browsing patterns, including subsequent page loads
  3. Lacks perspective on other locations
  4. May lack information on the source of an issue


  1. PageSpeed Insights
  2. Chrome Audit/Lighthouse
  3. WebPageTest
  4. GT Metrix

Live monitoring and alerts

The performance of a webpage can degrade very quickly. It can degrade due to poor network conditions, an influx of bot visitors from a new ad, a influx of legitimate visitors during peak hours, or from the deploy of a non-performant feature.

When the performance does degrade, you need to know immediately, so you can either roll back the deploy, or investigate the other factors that may be slowing down the site.

Notice that price isn't listed as a benefit (pro) or drawback (con) of live monitoring tools. You generally need to pay something to use these tools effectively, but usually that price is less than $100 a month, even on large sites.


  1. Real-time notifications of performance changes
  2. Easy to quantify
  3. Can be configured to request from other locations


  1. Limited information
  2. Lacks perspective over time
  3. May lack information on the source of an issue
  4. Fragile configuration can lead to false positives


  1. StatusCake
  2. Pingdom

Full stack observability

Some tools offer insights into the full page lifecycle over time. These tools are constantly ingesting data from your website and compiling that data into configurable visualizations. They look at page load data on the client side and server side using highly granular measurements such as database transaction time, and the number of http requests.

If you wanted a single source of information to measure performance on your site, then these tools are the only option. They can provide one time assessments, monitoring, and backend insights.

One big problem with these tools is that they are quite complex. To use these tools effectively, you need developers to help set them up, and you need data analysts to extract the important information exposed by these tools.


  1. Includes detailed breakdowns that can help identify the source of performance issues
  2. Includes data over time
  3. Highly granular data


  1. Difficult to use
  2. Expensive
  3. Requires developer setup and configuration


  1. New Relic
  2. Sentry

Qualitative user tests

The final approach for measuring the performance of a webpage is subjective. In other words, you must actually look at how your site performs when real people are using it. This can be as simple as opening a website on all your devices and trying to browse like a normal user, or you can set up time to interview real users and gather qualitative information about their experience.

I once worked at a company that required developers to attend in-person user tests every two weeks. This allowed every developer to see how users actually browsed and experienced their work. This may be overkill for most companies, but it's a perspective that can't be ignored.


  1. No additional tools are necessary
  2. Exposes actual, real world user experience
  3. Exposes issues raised from real browsing patterns including subsequent page loads


  1. It's easy to prematurely generalize from a small number of cases
  2. Can be expensive and difficult to do well
  3. Difficult to quantify
  4. Not timely


  1. Web browsers on multiple devices
  2. Google Analytics
  3. User testing services


In this article, I introduced four different ways to measure the performance of a webpage. Each of them is necessary to get a full understanding of the performance of a page. I also introduced some of my favorite tools that can be used for each approach.

The four approaches are...

  1. One time assessments
  2. Live monitoring and alerts
  3. Full stack observability
  4. Subjective user tests

I hope that this prepares you to start wading into the complex world of measuring website performance.