Dealing with Mutable Data

In JavaScript Objects are mutable, which simply means they can be changed. I think the first time I heard this statement I thought “Yeah, so big deal.”. Well, it can be a big deal if you don’t understand what that mutable nature means. It can cause unexpected issues.

In this tutorial that I recently published I talk about the issues you can run into and provide some examples. The examples shows how the mutable nature of objects can cause some unexpected consequences.

I then followed up this tutorial with a second tutorial that shows a possible solution. The solution is cloning objects. This is a technique commonly used in functional programming and is great to be aware of. I think the two tutorials together can be a great help.

What tutorials would you like to see?

Creating a Function that can Remember Data

I recently released a tutorial about creating functions that remember data. This can also be referred as “retaining state”. This is a great feature of JavaScript and it reflects what I feel is one of the strengths of JavaScript.

This technique uses closure, but it uses it in a way that my not be intuitive, even to those that understand closure well. The basic idea is that your invoke a function that returns a function, and that returned function has access to (remembers) any data that was passed to it or establish at the time the function was returned.

This can be a powerful feature. Take a few moments and watch the tutorial and then tell me what you think.

Storing Data in a Browser

At times you may come across the need to store some data in the browser so that when the user returns, you already have that data available. This can help solve a problem that might require the connecting and passing data to a server. But I have also found situations where even though I am passing data to a server it is helpful to store some data in the browser to ease the experience for the user.

I’ve recently published two tutorials on ways to store data in the browser. One uses localStorage and the other uses indexedDB.

LocalStorage is a pretty simple solution, but it does have some limitations such as the data can only be a string and there is a limit to how much data you can store. IndexedDB overcomes those limitations, but it is not quite as simple to use as localStorage.

Watch these two tutorial to dive deep into storing data in a browser.

Performing a Case-Insensitive Sort on an Array of Strings

I recently released a tutorial on the All Things JavaScript YouTube channel that dealt with higher order functions. Within the tutorial I used an example that dealt with forcing the sort method of Arrays to do a true alphabetic sort. By itself, sort does not do this.

Here is the problem with sort. Lets say I have an array of strings like this:

let things = [‘Building’, ‘Car’, ‘house’, ‘tree’, ‘bicycle’, ‘automobile’];

It will not sort correctly if I use:


The reason is that I have a mixture of upper and lowercase characters. The uppercase characters will sort first and we end up with this.

‘Building’, ‘Car’, ‘automobile’, ‘bicycle’, ‘house’, ‘tree’

The solution is pretty simple; we just need to sort with the correct case. However, executing on that solution is not quite as simple. There are a number of different ways to do this. In the tutorial I chose to take advantage of a little known feature of sort; you can pass in a function to the sort method that can be used to determine the sort order. That makes sort a higher order function, and that was the reason I was using it as an example in the tutorial.

The end result is kind of cool.

If you would like to understand higher order function better or you are interested in the sort solution, take a look at this tutorial.

Dealing with Special Characters

The back slash character has special meaning in JavaScript strings. It is an escape character that allows us to enter special characters that would be difficult to enter otherwise.

Now most of my life I have been slash deficient. When someone says forward slash or back slash, I don’t know which character it is. Some have tried to explain it by telling me to imagine a person leaning backwards or forwards. But that doesn’t help me at all because I don’t know which side has the face.

Anyway, I digress. This is a back slash (\). Now we are all on the same page. This character allows escape sequences in strings that can insert special characters. JavaScript has some default escape characters, but the real power begins when you use unicode or hexadecimal character codes. To specify a hexadecimal character enter \x and then the hex code. For unicode, enter \u and then the code.

I think the biggest trick with these charaters is knowing the code to enter to get a certain character. Here are a couple of websites that have unicode and hexadecimal codes for characters:

Once you have a list of codes, most people are good to go. But if you need a little more guidance, here is a recent tutorial on special characters in JavaScript.

What the Heck is Memoization?

OK, I admit it. I went through a phase when I first heard the word memoization where I ignored that it existed. After all, what could a technique with a name like that have to offer me?

Well, I finally threw away my pride, admitted it might be valuable and spent some time learning about it. Yes, it is a technique used in functional programming, but it is a technique that can be applied to any coding paradigm. And it can be quite valuable.

So to make my penance complete, I thought it appropriate to do a tutorial on memoization.

Now don’t let the term scare you off. It really is not a complex concept. The patterns for implementing it are a bit involved, but the concept itself is pretty easy to understand.

I just published the tutorial on memoization and you can access it below. Take a look and give me your thoughts.

Functional JavaScript

Functional programming in JavaScript has been a topic of considerable discussion for some time now. Several books have been published about functional programming in JavaScript and there are developers that use this approach almost exclusively.

Whether or not JavaScript is a functional programming language is beside the point now because so many people are using it for such.

I don’t know enough about functional programming to teach the ins and outs of that particular approach. However, what I do know is that functional programming has some very valuable concepts that you can draw on to improve your code. I’m advocating a pragmatic approach to functional programming in JavaScript. In other words, use elements of functional programming that you find valuable.

So this begs the question, how to get started? Well, as mentioned there are several books published about the subject, and I will be reviewing some of those in the future. But I think a great first step is to really understand some of the methods of the Array object. These methods were designed around functional programming concepts. For example, map, forEach, every and reduce are a few that are valuable to understand. And it just so happens we have a tutorial on some of those methods.

What are your thoughts on functional programming in JavaScript?

You can find the tutorial here:

Exception Handling

Exception handling is an important aspect of JavaScript coding. I know that when I first learned exception handling, it opened for me new horizons on how I could approach problems. If an exception occurred because of circumstances that were not ideal, I could react to that exception and still keep my programming running.

The main mechanism for exception handling in JavaScript is the try catch statement. It is great for exception handling, but it is also possible to use try catch in situations where there is not an exception.

I just completed two tutorials on exception handling. The first shows how to use try catch statements in your code. The second talks about when you should and should not use try catch.

Take a look at both videos and if you have any additional rules to add for using try catch statements post them here.

Obfuscation in JavaScript

I love the word obfuscation. It seems to reflect its own definition. To obfuscate something is to make it difficult to understand.

So why would we want obfuscation in JavaScript. Well, let me give you an example. Recently I was working on a project where we had to connect to an online system. The online system did not have the security fully implemented yet, and as a result we had to include some of the details about the system in the JavaScript code. Well, we didn’t want it to be super simple for someone to discover that information. We wanted to hide it a bit. So the solution…we obfuscated that portion of the JavaScript code.

I learned about a couple of sites that help do this. They obfuscate your JavaScript code by moving things around and converting information to Hex. I used both of these locations. I would pass the code through the first location and then pass the results through the second. Technically, someone could figure it out, but it is quite difficult. Drop some code in, obfuscate it, and then see if you can make heads or tails of it.

Objects, the Center of the JavaScript Universe

When someone says that JavaScript is not an Object Oriented Language, what they really mean is that JavaScript doesn’t use the approach to object orientation that they are used to. It doesn’t use classes. It is not necessary to create a class in order to instantiate an object. To me that is a big advantage with JavaScript.

To say that JavaScript doesn’t use objects is very far from the truth. I will put it this way: it is almost impossible to do anything of value using JavaScript without using objects. Everything but primitive values are objects. Arrays are object. Functions are objects. A regular expression definition is an object. A date value is an object. And it goes on and on.

So objects are central to everything in JavaScript. Because of this point I have started compiling (in the form of a playlist) a bunch of tutorials on objects in JavaScript. There are numerous topics that could be covered with objects, so this compilation is not complete, but that is what I would like to work towards.

If you haven’t taken the time to really sink you teeth into objects and understanding the object oriented nature of JavaScript, you need to! It needs to happen sooner rather than later. You can start with this playlist.

Then get a book on objects in JavaScript and dive deeper. I have reviewed a couple as a part of this blog. Here are two good ones.