Javascript quick filter, map and reduce

Again part of my breaking out of jQuery and back into vanilla JavaScript

Filter, Map and Reduce examples

const dragonEvents = [
 {type: 'attack', value: 12, target: 'dorkman'},
 {type: 'yawn', value: 40},
 {type: 'eat', target: 'horse'},
 {type: 'attack', value: 23, target: 'fluffy'},
 {type: 'attack', value: 12, target: 'dorkman'},
 {type: 'attack', value: 3, target: 'dorkman'},
 {type: 'attack', value: 10, target: 'dorkman'}
]

const totalDamageToDorkman = dragonEvents
 .filter(event => event.type === 'attack')
 .filter(event => event.target === 'dorkman')
 .map(event => event.value)
 .reduce((prev, value) => (prev || 0) + value)

const targets = dragonEvents
 .filter(event => event.target)
 .map(event => event.target)

const findFluffy = dragonEvents
 .filter(event => event.target === 'fluffy')

const totalAttackPoints = dragonEvents
 .filter(event => event.value) // Filter out null or undefined event.value
 .map(event => event.value) // Push to the new array only event.value
 .reduce((total, event) => (total | 0) + event) // Sum the array
 // .reduce((total, event) => { return total + event}, 0) //Does the dame thing but specifies starting value
 
 console.log('Total:\n' + totalDamageToDorkman);
 console.log(JSON.stringify(targets, null, 2));
 console.log(findFluffy);
 console.log(totalAttackPoints);

Tanks to Fun Fun Functions and Mattias Petter Johansson

JavaScript fetch()

In a previous post I was refreshing my memory with vanilla JavaScript  after years of jQuery-ing, especially AJAX request and the

XMLHttpRequest()

My eyes rolled when I was reading more about it then  I found fetch()  ( I know its been about since 2015 and now almost universally adopted).

Fetch does what XMLHttpRequest does but in a more elegant way and DOES NOT need additional libraries as it is bundled with JavaScript. It also makes use of “promises” .

const url = "https://randomuser.me/api/?results=10";

fetch(url)
.then(function(response) {
 return response.json();
})
.then(function(data) {
 console.log(data.results);
})
.catch(function() {
 console.log("Booo");
});

The above code queries the URL, then parses the string as JSON, then does something with the data.

It also catches errors.

Good eh?

Its looks to be easy to expand and do all manner of fetching. For example submitting a form

var form = new FormData(commentForm);
fetch( url, { method: "POST", body: form })

You can then chain .then() promises to get the desired outcomes.

For more information

A quick introduction video from Google

From Google Working with the Fetch API

Jake Archibald’s post Thats so Fetch

Scotch post The Fetch API

 

 

 

 

 

strpos() not working?

PHP strpos() not working as expected? It could be a  “non-strict” comparison problem.

When using strpos() to determine whether a substring exists within a string the  results can be misleading: Remember FALSE == 0?

Consider the following:

$quote = 'Dave rocks';
 
if (strpos($quote, 'Dave')) {
    echo 'Dave is awesome.';
} else {
    echo 'Dave is not awesome.';
}

strpos() Returns position is 0 ( zero ) that is evaluated as FALSE so, “Dave is not awesome”.

Much better. In this case adding the strict comparison === ( 3 equals ) to the “if” statement asks if strpos() returns a number and  is not strictly FALSE. So, “Dave is awesome”

$quote = 'Dave rocks';
 
if (strpos($quote, 'Dave') !== FALSE) {
    echo 'Dave is awesome.';
} else {
    echo 'Dave is not awesome.';
}

For more see PHP.net

 

 

 

Laravel Pagination

Pagination with Laravel (5.4 at the time of writing) is very easy.

Say you want a table of users

In your controller:

$user = User::all()->paginate(10);

In the view loop through your users as normal and then add

$user->links() where ever you feel like it and more than one place if you are feeling dandy.

There is more..

But say you want more than one paginate-able list/table on the same page? This is the paginators signature

paginate($perPage = null, $columns = ['*'], $pageName = 'page', $page = null)

Easy, extending the original query lets get all the threads/comments for a user. Assuming your User model can dish out Threads and Comments

$user = User::find(1);
$threads = $user->threads()->paginate(4, ['*'], 'threads');
$comments = $user->comments()->paginate(4, ['*'], 'comments');

Then in your view loop through your comments and add

$comments->links();

Loop through your threads and add

$threads->links();

 

 

 

New querySelector() and querySelectorAll()

Catching up with JavaScript after years of using jQuery I found these two shortcuts for replacing longer getElementById() methods. NOTE: the querySelector is passed an ID in the CSS format

<button id="our-button">Add New Item</button>

<script>
    // These are both the same
    var ourButton = document.getElementById("our-button");
    var ourButton = document.querySelector("#our-button");
</script>
<ul id="our-list>
    <li>A thing</li>
    <li>Another thing</li>
    <li>A new thing</li>
</ul>


<script>
// These are both the same
   var listItems = document.getElementById('#our-list').getElementsByTagName("li");
   var listItems = document.querySelectorAll("#our-list li");
</script>

 

 

Javascript AJAX without jQuery

I learnt this stuff years ago but with the rise of jQuery I like many others had become lazy. Add the fact that so many browsers handled things slightly different going down the library route had its benefits.

It is 2017 and things have improved many jQuery(ish) approaches have been adopted by Javascript and browsers have become more similar.

So here goes. First off a GET request to retrieve a Chuck Norris joke

<script>
var url = "http://api.icndb.com/jokes/random";
var request = new XMLHttpRequest();

request.open('GET', url, true);

request.onload = function() {
 if (request.status >= 200 && request.status < 400) {
 // Success!

printJokes(request.responseText);

} else {
 // We reached our target server, but it returned an error
 console.log('There was a problem. Status:' + request.status);

}
};

request.onerror = function() {
 console.log('There was a problem!');
};

request.send();


var printJokes = function(jokes){

JSON.parse(jokes, (key, value) => {
 key == 'joke' ?
 console.log(value) : ''
 });

}
</script>

 

 

 

Toggling in Javascript, PHP and possibly other environments

For a long time if I wanted to change the state of a variable between true and false (toggling). In PHP I would do something like…

$switch = true;
if($switch == true){
    $switch = false;
}else{
    $switch = true
}

That worked fine, then there came Ternary shorthand

$switch = true;
$switch = ($switch == true ? false : true);

Not bad eh? Much easier to read. Then came this

$switch = true;
$switch = !$switch;

If you read it out loud it sounds like, ‘Switch is not true?’ So the answer would be either

True = $switch is false

Or

False = $switch is true

Javascript reminder #1 Spread syntax

Okay, a quick reminder on Spread Syntax

If you have a Javascript function that you call with

average(1, 2, 3);

function average(x, y, z){
// Average of the three numbers
}

You are limited to just three properties/arguments. Not very useful if you have more or less numbers you want to find an average. Using Spread Syntax we don’t have to worry about the number of values passed

function average(...args) {
  var sum = 0;
  for (let value of args) {
    sum += value;
  }
  return sum / args.length;
}

average(2, 3, 4, 5); // 3.5

The Spread Syntax ( the three dots{name}) includes all the unknown values.  It gets better still

var averageMethod = 'mode';
var roundTo = 2; /Decimal places
doThing( averageMethod, [2,4,3,6,10,19], roundTo);

function doThing(method, ...valuesToAverage, roundTo)
{
// Calculate averages
}

And Spread Syntax can be used when creating arrays

var parts = ['shoulders', 'knees']; 
var lyrics = ['head', ...parts, 'and', 'toes']; 
// ["head", "shoulders", "knees", "and", "toes"]

Good eh?

 

Composer – Init, Install and update

Assuming that composer is installed on your machine what next?

If you do not have a composer.json file lets create one. In your command line ‘cd’ into your projects root folder. Then type

composer init

and answer the questions. Easy.

Look at your projects root directory and you will see a composer.json file. This is where you can add/remove packages, set namespaces, set files that are always load, run scripts, and lots of other good stuff.

Do you see a vendor/ directory? No? At this stage type

composer install

This actually ignores the .json file and reads or creates a composer.lock file then installs all the packages and dependencies required ( as well a bunch of other stuff – see the end of the post). The lock file is important when there are multiple developers/users it ensures that we/you are all using the exact same versions of installed packages.

Now lets pretend that you have cloned a project from GitHub that uses composer. You wont see a vendor/ directory but you will have a lock file.

composer install

Now you have a vendor/ directory and all is right with the world.

If you try and  run install again it won’t do anything ( try it if you want )

If you want to add packages use the

composer require name\package

If you want to update the composer files and logs

composer update

Updates your dependencies to the latest version according to composer.json, and updates the composer.lock file.

“A bunch of other stuff”

Composer can do a whole lot more. Including

  • Running scripts after installing, updating, etc
  • Autoload files. For example helper files with common functions
  • Pulling packages from GitHub. Great if you are writing your own
  • Lets you have a development environment and production sets of packages. E.g. so you can have PHPUnit just on your local machine.

Laravel Real-Time Facades (Bastards!)

Come on Taylor Ortwell whats the deal? I spend time learning about Facades and their round-a-bout method of getting them registered and running. Now with Laravel 5.4 I can get the same outcome by typing a single line of code.

WTF?

What is a  Laravel Facade?

A Facade is a “static” interface for classes that are available in the application’s service container. Think functions on steroids!

Creating them WAS simple but there where a few loops you had to jump through. But now just declare them using the Facades namespace

use Facades/{location}/{of}/DoSomething;

and use them with

DoSomething::amazing()

No need to register your Facades. Just like before DI is taken care of.

 

Laravel Lovelyness

 

In case you don’t get it I think this new method of declaring Facades is a good thing.