JavaScript’s cryptic ‘this’ – what, when and why

*Photo by Tarun Ram on Unsplash

Before MDN started to organize their JavaScript documentation, finding answers to your JavaScript questions often landed you on Stack Overflow.

Welp, these days MDN has mostly done away with that practice, that is, except if you’re looking for answers around the usage of JavaScript’s this keyword.

The documentation is great, it really is, but it’s not exactly full of helpful, real-world examples. So I thought I’d put together a few tips and tricks about the ever so magical this keyword.

Old-skool JS

“Back in my day we had to alert out our objects!”

Ok, so yeah, if you run console.log(this) in your dev console you’ll generally see that by default, this = Window{}. Super helpful…😏

It gets more interesting when you check the value of this inside a function:

function mahFunc(){
    console.log(this);
}

mahFunc();
// Window{}

You should still see the Window object. Ok so, nothing new here.

But what if you add 'use strict'?

function mahFunc(){
    'use strict'
    console.log(this);
}
// undefined

Hmm.

Ok now, but what if you call mahFunc() on the Window global (since it’s a global function)?

function mahFunc(){
    'use strict'
    console.log(this);
}

window.mahFunc();
// Window

Huh?

Strict mode is a funny beast, but it generally makes errors more obvious and cleans up your JavaScript. Something not mentioned in the MDN docs is that bundlers/loaders/concatenators like Webpack/Browserify, may have strict mode enabled by default. You might end up with some wacky loader that enables it with out you knowing. So keep an eye out if you ever see your this call returning something funny.

Call me plz

Ok so this in a global context is weird, but who doesn’t use objects and ES2015 classes these days? If you’d like to use a different value for this, (as-in not undefined or Window) inside your function, you can pass a context with .call() and .apply(). I always remember these with ‘yadda-yadda.prototype.call()’.

function mahFunc(){
    console.log(this);
}

const config = {

    stepOne(){
        //do step one
    },

    stepTwo(){
        //do step 2
    }
}

mahFunc.call(config);

//{stepOne: ƒ, stepTwo: ƒ}

And there you go. this references the object passed in argument to .call(). Cool right?

This way you’re able to specify a context for a function. It’s super handy and what a lot of frameworks and bundlers use internally – check out your Webpack bundles!

I won’t go over all the possible cases/uses of this, there’s quite a few and the MDN doc is really good.

It’s important to remember this 🙄.

Open Source, PHP and Visual Studio Code

Lately, VS Code has been getting a lot of hype in the dev community. It’s been around since for a few years and TBH is a really sweet editor. Lots of great extensions and community support. It’s also quite fast (for an Electron app 😬) and the peeps and Microsoft seem to be keeping it up to date and iterating quickly.

However, anything you really need to work with PHP is missing by default. I believe this is by design to encourage a vibrant extensions community. Luckily, like most languages, there’s a vibrant open source PHP extension community. There’s a few great extensions for PHP: PHP IntelliSense, PHP Debug (both by the same developer) as well as PHP Intelliphense (#wat?). There’s even a really great intro by Jeffrey Way on Laracasts outlining everything you need to do to get VS Code set up for PHP dev.

Some of the PHP packages work fine and have over a million installs (!!!). Sometimes, however, they don’t work. Like, at all. Just today, the PHP Debug extension completely broke. Luckily the developer was paying attention and rolled out a fix within hours. Pretty awesome support for an open-source product!

However, if you paid for the editor, say something like PHPStorm, you could go and raise an issue on their support channel. You could complain about the product not working, rightly so, as you’ve paid for the right! As a ‘customer’ you have a certain amount of clout with a vendor like Jetbrains. This is NOT the case with open source, and I feel that we developers forget this.

This is where I take issue. I’m all for open source software. I’ve built my career on it. The issue is that the developer for this plugin had to fix the issue himself. There’s an expectation there that he HAS to fix the issue, and do it RIGHT NOW. And if it’s not done immediately people freak out, complain on Twitter, write a blog post about, have a cow 🐮, man.

Open source is just that, open. If you find an issue with a plugin, editor, extension or WHATEVER, see if you can fix it! That’s the whole point. Let’s not throw our hands up and complain, let’s get our hands dirty and fix the damn thing.

That’s what open source is all about. Let’s remember that.

/rant

PHPStorm, MAMP and Xdebug – How to keep (some of) your hair

I’m mostly logging this here for my own benefit, but if the Google gods brought your here, sweet!

Just came across another fun quirk with running Xdebug, MAMP and PHPStorm together. 😅😅😅😅

I’ve talked about this combination causing me issues in the past, but this is a whole new situation that killed a couple hours for me.

So, it appears that for PHPStorm to pick up Xdebug correctly, the xdebug.remote_host variable needs to be set correctly. It normally is, if you copy-pasta some of the tutorials on the internet.

Unfortunately, for some reason, this Monday morning, setting this value to localhost no longer worked. Why? Welp, localhost is pointing to an invalid folder location, according to MAMP. Apparently this was enough for PHPStorm to freak out and just not run Xdebug. Period.

Fun!

So how’d I figure out this was the reason for Xdebug throwing up?

The PHPStorm docs of course! Wayyyyy at the bottom of this page it’s plainly stated:

Remote host is configured as ‘localhost’ despite server host is probably not local

The URL to validation script contains something different from localhost, but the xdebug.remote_host value is not set and so is using the default value of localhost, or is set to localhost or 127.0.0.1.

#themoyouknow

JavaScript build tooling and the CLI

Something that’s come up recently in the front-end world is the topic of a learning curve and JavaScript tooling such and Webpack and Babel. While I agree that new tooling can sometimes be a pain to learn, since when did being a web developer/programmer/rockstar not require learning new things? I mean, learning the CLI is one thing, but it’s not suuuuper difficult and is definitely a skill that will serve you well in your career. On top of that, front-end build tooling has been around for a while, first with Grunt and then Gulp. Does Webpack make things that much more difficult?

The argument I’m making is partially around React and how Webpack (or similar) is required. To me, this doesn’t seem like a problem, as many languages require compilation during a build step. I see the build step and associated tooling a good thing, as it allows for more streamlined and complex programming concepts to be brought into front-end development.

If you’re worried about learning something like the Webpack build process, Create React App has got all the setup jank covered. In Vue, there’s vue-cli which similarly gets you set up. In both cases all it takes to get up and running is npm install then npm start. That’s not too bad!

I guess what I’m saying, if all this ‘new’ stuff bothers you as a developer, it might be time to 1.) upgrade your skills, or 2.) do something else. Things aren’t slowing down any time soon in the front-end landscape, better get on the wagon or jump off!

Hey Linode!

After getting my VPS shut down for a second time by Digital Ocean (which apparently was issuing DOS network packets – no further explanation from DO), I decided to give Linode another whirl.

And here we are.

Running Ubuntu 16.04 LTS and it’s a smooth as butta.

Software for now:

  • nginx 1.10
  • PHP 7.0.8
  • MySQL 5.7.15

Will also probably get Node v6 running up there soon too.

MAMP, Xdebug, PHPStorm and symlink madness

Ask any PHP developer and they’ll tell you Xdebug is the best thing since sliced bread. While true, it’s also one of the biggest pain in the asses to setup. I’ve probably set it up, in various incarnations, close to 10 times.

There’s always something that get’s me caught up and messed up. This time I decided to document how I was able to get it working this time, so hopefully I don’t have suffer through this again.

I followed Michael Novotny’s post on this, and it almost works. There’s just one missing piece, for me, and that was how to handle symlinks in your plugins.

This overview assumes a few things. You’re on a recent version of OSX, you have MAMP Pro 3 installed, and you’re using PHPStorm.

Step 0: Use the same version of PHP for your CLI and your webserver.

Time and again I’ve seen people have issues with their CLI PHP version and Web server PHP version not matching up. This can cause all sorts of weirdness, especially with Xdebug, so make sure you’re using your MAMP version of PHP on your CLI.

This can be as simple as adding the MAMP PHP version to your $PATH.

In your ~/.bash_profile file you can add something like this.

echo $PATH | grep -q -s "/Applications/MAMP/bin/php/php5.6.10/bin"
if [ $? -eq 1 ] ; then
export MAMP_PATH=/Applications/MAMP/bin/php/php5.6.10/bin
export PATH="$MAMP_PATH:$PATH"
fi

Step 1:Make sure Xdebug is installed.

This one’s a gimme, but still a point worth making to cover all the bases. Make sure you’ve got Xdebug running and remote_enable=1 is set in your php.ini. There’s plenty of resources on the inter-web’s for this.

You can check if Xdebug is available, by running php --version in your CLI. You can further check what kind of Xdebug settings your have enabled by running php -i | grep xdebug

Step 2: Setting up PHPStorm

Make sure PHPStorm is using the same PHP Interpreter you’re using for everything else. You can set this in Preferences > Languages & Frameworks > PHP and selecting the MAMP PHP version you’re using.

Interpreters_and_Preferences_and_wpmdb-replace_php_-_wp_-____Sites_wp_

After that, essentially follow Michael’s guide for setting up PHPStorm with the debug configurations, once PHP is all set up.

Step 3: Symlinks

If you’re using plugins in your local PHP install that are symlinked (and many plugin developers do this), make sure you map those folders for Xdebug and PHPStorm! This is where I got caught many times. I even needed to map the base of my WP install, since I had checked the ‘Use path mappings’ setting.

Servers_and_Run_Debug_Configurations

For me, that’s all it took to get things running. Without the explicit path mappings for the symlinks, Xdebug half worked – which was super confusing…

I should note that if you’re running multiple sites on your MAMP install, and 2 of these sites are talking to each other in any way (via AJAX or the WP Rest API etc.), make sure ONLY ONE is running Xdebug. Not sure what the reason is, but the workaround is easy enough. Just use another version of PHP within MAMP, one that doesn’t use Xdebug.

Hope this helps someone else.

WordPress Jetpack contact forms – AJAX

EDIT, May 9, 2016

I noticed that the form wouldn’t submit when not logged in, so I’ve updated the gist to include a check to see if a user is logged in. 


Jetpack is awesome for a lot of things. Unfortunately, one of the things that it isn’t so great for is submitting it’s contact form via AJAX. I’ve looked into this before and decided I might as well hack something together that ‘kind of works’ ™.

Here’s the full working code, I’ll go into a bit below:

Basically, all you do is fake-send the form via ajax, parse the returned page’s HTML and look for an H3 tag with the submission message.

Easy-peasy…

Linux – Blocking bad IPs

This is more an informational post for myself, but here’s some nifty commands that help debug what’s going wrong on a server when things aren’t going right.

netstat -t
netstat -tn

These are good for watching WHO is hitting your server and what their IP is. netstat -tn shows the unresolved address, so you should get the IP’s of possible spammers

Once you’ve got the IP(s) you can block them with iptables like so:

iptables -I INPUT -s <IP ADDRESS> -j DROP

Another good tool for watching network traffic is iftop. You’ll need to install this one via Yum or Apt though:

 iftop -N -i eth0

1__ssh

And for overall machine health, nothing beats good old htop! Ahh, CPU usage back to normal.

1__ssh