isNaN is not the same as Number.isNaN

Since JavaScript is an untyped programming language, a variable can contain data of any type at any time. But sometimes you need to know what type the data is. Something I have done in the past, is use the isNaN function for this.

Take this (bad?) example. If the variable myData is a number, then we want to format it to 2 decimal places. Otherwise, we just want to display it as is. One way to do that would be:

if (isNaN(myData)) {
   displayString(myData);
else {
   displayDecimalNumber(myData);
}

But then along comes the linter complaining about isNaN:

So I blindly accept its suggestion and change it to Number.isNaN. But now there's a problem because now it's trying to format my string data as a number. What happened?

The problem is that the global isNaN does not behave the same way as Number.isNaN.

The global isNaN function converts the value to a Number, then tests it.

Number.isNaN does not convert the value and will return true for any value that is not of type Number.

So maybe a better way to write this code would be:

if (typeof myData === 'number') {
   displayDecimalNumber(myData);
} else {
   displayString(myData);
}

Implicit Argument to JavaScript Promise

I came across some code at work that I did not understand. After doing a little digging, I learned something I did not know about Promises. If you have a single argument to a function, you can use an implicit argument. What does the mean? Let's start with an example:

test(0)
 .then((results) => test(results))
 .then((results) => test(results))
 .then((results) => { console.log(`Results from first test: ${results}`) });

function test(arg) {
 return new Promise((resolve, reject) => {
  resolve(arg + 1);
 });
}

So what's happening here? I am passing the number zero to the function test. It is taking that number, adding one to it, and returning a new Promise. .then((results) => test(results) then takes that result and passes it to the test function again which again adds one and returns a new Promise. Finally, we are printing the result which is 3. Now here is a different way to write that code with an implicit argument:

test(0)
 .then(test)
 .then(test)
 .then(results => { console.log(`Results from second test: ${results}`) });

function test(arg) {
 return new Promise((resolve, reject) => {
  resolve(arg + 1);
 });
}

The result is the same. In this case, .then(test) is the equivalent of .then((results) => test(results)). This shorthand notation only works for a single argument. If you have multiple arguments to your function, you will have to write out the full code.

MySQL Subqueries

For most of my software development career, I used an Oracle database. At my current job, we use a MySQL database. So I am still learning the ins and outs of MySQL. Here is a common thing I would do in Oracle:

SELECT
  name, total_points
FROM (
  SELECT
    name,
    SUM(points) AS total_points
  FROM
    scores
  GROUP BY
    name
)
WHERE
  total_points >  10
ORDER BY
  total_points DESC, name

That would give me a list of all players who have scored more than 10 points. When I tried this same format in MySQL, I got this error:

Error Code: 1248. Every derived table must have its own alias

After a little searching, I came up with the solution. I had to name my inner query. So with a slight modification it worked:

SELECT
  tp.name, tp.total_points
FROM (
  SELECT
    name,
    SUM(points) AS total_points
  FROM
    scores
  GROUP BY
    name
) tp
WHERE
  total_points >  10
ORDER BY
  total_points DESC, name

Accessibility and Social Media Management

There is a local radio program that I used to listen to that gives advice on yards and gardening. The host is very knowledgeable and is my go-to resource when I have questions about planting, fertilizing, and weeding. Here was an exchange this morning between (presumably) the social media manager for his account and one of his followers regarding a video that was posted:

The follower asked a simple question but got back a seemingly harsh response. First, let's look at why the follower may have misunderstood the audio.

• · Maybe the follower is hard of hearing
• · Maybe the follower's native language in not English
• · Maybe the follower was in a noisy environment
• · Maybe all of the above are true

The response from the author did not take any of these things into account. That is why accessibility is important not just for us web developers but for content providers as well. A better response might have been:

Thank you for your question. He was saying "rose soil". Here is an example of a product that we recommend.

Here is another thing to consider. Various sites such as this one report that 85% of Facebook videos are watched without sound! Additionally the World Health Organization reports that globally over 400 million people suffering from some sort of hearing loss. So if you are relying solely on audio on your site to get your message across, you are alienating a large group of people. This is why it is so important to provide captioning on your social media videos.

I realize that not everyone will have the skills, times, and/or technology to caption their videos. So in that case, a good fallback plan when someone poses a questions about the audio is to just be kind.

Git Status on Command Line Does Not Match Git Status in VSCode.

A couple of times recently I ran into a situation where VSCode was showing a lot of untracked files in git but the command line was not. Today when I opened up VSCode, it showed over 60 untracked items while the command line only showed 15. It turned out to be a simple misunderstanding on my part.

To demonstrate, I created a new git project with a new subdirectory called new-dir. Inside of new-dir, I created 3 files.

When I run git status on the command line without any parameters, it collapses new directories into single entries.



By examining the git output in VSCode, I see now that it is running the command git status -z -u. The -z just terminates each entry in the list with a NUL instead of LF presumably for better parsing. The -u lists out each untracked file individually. And this makes sense because in the source control window of VSCode, you want to be able to see the diff of each file individually.

What I Learned from the Job I Didn't Get

Recently I had the unique experience of talking face-to-face with the person who beat me out for the job we both interviewed for. I want to share what I learned from this situation but first let's back up to the beginning of the story.

In 2001 I accepted a job working as NASA's Johnson Space Center as a software developer. I was equally parts shocked and excited when they offered me the job. Over the next 15 years I would have a great career working there. In May of 2016 when our contract was renewed, the government changed some things up from the previous contracts I had been on. Long story short, I ended up with a significant pay cut. It had already been 3 years since my last pay raise due to budget cuts. And with Congress at an impasse more and more, government shutdowns were becoming a regular threat. So for those reasons and others, I decided to start looking for a new job.

In July of that year, I got a call from a recruiter that had found my resume online. He told me about a frontend developer job just down the road from NASA. He got me an interview and I felt pretty good about it. Afterwards he told me that I was their first choice based on my resume and experience. However, after a few weeks went by and I heard nothing, I contacted the recruiter to get a status. He told me that they had decided to go with someone else. I was shocked, although in retrospect I shouldn't have been. I had done a terrible job of selling myself.

I also had a revelation after that: I had not dedicated enough time to professional development. In a perfect world, an employer will make professional development a priority for their employees. But we don't live in a perfect world and so the onus was on me to keep up. And I had not. Over the next couple of years I would take to Twitter, newsletters, and online training to educate myself on the latest and greatest tech in frontend development. I landed interviews with several companies during that time (sometimes even multiple interviews) but couldn't seem to get an offer. I finally decided to take a break from the job search.

About the time I made the decision to quit looking, I got a call from that company I had first interviewed with in 2016. They wanted to know if I'd be interested in interviewing for a developer job. I interviewed with some of the same people I had interviewed with before. And this time, I got an offer. I accepted the job and with much sadness, I left NASA after 17 years.

One day I realized that my coworker DJ (not his real name) was the person who had beat me out for the frontend developer position two years earlier. So I asked him about it. He told me that when he had interviewed for the job, he built a small prototype to demonstrate his skills. I really think this extra initiative on his part was what won him the job.

Lessons Learned

Professional Development

The world of web development is changing very rapidly. I had let my success at NASA stagnate me. I did look at new technologies from time to time, but I wasn't making a concerted effort to study and learn. That was a mistake. Take a little time every day out of our schedule for professional development.

Interviewing

Don't expect your resume to do all of the talking for you. I have a really hard time talking about myself. I don't like to draw attention to myself. But when you are interviewing, you have to do this. Build an online portfolio to show your work. Do something to make yourself stand out. For one job I applied for, I incorporated the company's colors and logo into my resume. The interviewer mentioned that it caught his eye.

It Will Take Some Time

When I first started interviewing, I thought it would take a few weeks maybe a couple of months at most to get an offer. I had no idea it would take two years! Be patient. Don't get your hopes up too high. Sometimes an interview will go great and you'll still get passed over for the job. That's ok. That job might have sounded great but maybe it wasn't so great. Maybe the people were difficult to work with. Maybe the management was unreasonable. Maybe the company is about to go under. Just assume that if you didn't get the job, it was for good reason.


Oh and for the record, I think hiring DJ over me was definitely the right decision. :)