Passing JavaScript arrays by reference and valuies

By default JavaScript arrays are passed by reference. See the code below. Notice that when a value in the 'firstArray' is changed, the corresponding value in 'secondArray' is also changed.

var firstArray = ['first','second','third'];
var secondArray = firstArray;

firstArray[1] = 'second most';

for (var i = 0; i < firstArray.length; i++)
{
  console.log(secondArray[i]);
}
/* Output
first
second most
third
*/

To overcome this issue you need to use the 'slice' method. This will pass the 'firstArray' to the 'secondArray' by value. See, in the output, that although a value in the 'firstArray' has changed, this hasn't affected the values within the 'secondArray'.

var firstArray = ['first','second','third'];
var secondArray = firstArray.slice();

firstArray[1] = 'second most';

for (var i = 0; i < firstArray.length; i++)
{
  console.log(secondArray[i]);
}
/* Output
first
second
third
*/

Fast lightweight web development on an old laptop

I was given an old laptop. It's quite handy for doing a little development when it comes into my head. Below I explain how I set it up.

OS

The laptop has a 32-bit architecture so I downloaded Lubuntu from https://lubuntu.net and replaced the slow Microsoft Windows installation.
There was one downside to this. Since Microsoft bought Skype, they have stopped supporting it's 32-bit version. Not so much of a problem for me as I have another laptop I use for more serious work, but worth noting.

PHP & Web Server

I installed PHP, but not the rest of the LAMP stack. PHP comes with a lightweight server which you can run from your working directory from the command line with the cli call of:
php -S localhost:8000
After doing that, just open up your favourite web browser and use the address http://localhost:8000

Sass

CSS has become a bit cumbersome now. I use Sass to make the process of producing stylesheets a little easier.
To install this on Lubuntu use:
sudo apt install ruby-sass
Once the install has completed you're ready to use it. First, your terminal change to the directory of your app e.g.
cd /home/mick/htmlstuff/myapp
You'll need at least 2 files for Sass. In this example we'll use custom.scss (the one we'll be editing) and custom.css (the output file which is referred to by your HTML page). Then you want to put a watch on custom.scss to produce custom.css. This again is done from the terminal with the line:
sass --watch custom.scss:custom.css
Now every time you update and save custom.scss, custom.css will be updated.

Editor

I now use Atom as my editor. To install it on Lubuntu, first add the PPA thus:
sudo add-apt-repository ppa:webupd8team/atom
Then do an update and the install through:
sudo apt update; sudo apt install atom
I had a graphic problem with mine at first. It kept flashing. To remedy this I changed the command of my Atom launcher to:
/opt/atom/atom --disable-gpu
Once Atom has been installed successfully it's time to add a few extensions. I recommend the following:

• browser-plus - This will open up a browser inside the editor and will display changes your project live, on save.
• file-icons - This provides more informative icons for the various files within your project.
• platformio-atom-ide-terminal - This will open up a terminal inside the editor. It's quite useful because some commands, such as the sass one above provide you with error messages.
• remote-sync - This will allow you to edit remote files through ftp etc. It's also particularly good because you can list all the files which shouldn't be synced.

jQuery media queries plugin

Media queries are really useful in CSS, but what if you could use them to control page events and content using jQuery. I have created the beginnings of a solution below.

Here we have 2 files:

• index.html
• mediaquery.plugin.js

index.html is a very basic page which passes the window object to mediaquery.plugin.js.

mediaquery.plugin.js listens for changes in the window width and reacts accordingly.

In this case it simply changes the background colour of the body which calls the plugin, but of course, this is only the start. In place of changing the page colour, you could do all sorts of useful things. For example, you could pass the identifier of a div the plugin and add external content to it. The list is endless. Have fun!

index.html

<!DOCTYPE html>
<html lang="en">
<head>
<title>jQuery media queries</title>
</head>
<body>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script src="mediaquery.plugin.js"></script>
<script>
(function()
{
    $(window).mediaquery();
})();
</script>
</body>
</html>

mediaquery.plugin.js

(function($)
{
    $.fn.mediaquery = function(options)
    {
        var defaults =
        {
            phone:'blue',
            tablet:'red',
            desktop:'green'
        };
        options = $.extend(defaults, options);

        $(this).handleWidths(options);
        $(this).resize(function()
        {
            $(this).handleWidths(options);
        });
    }
})(jQuery);

$.fn.handleWidths = function(opt)
{
    if($(this).width() < 481)
    {
        $(this).phoneFunc(opt.phone);
    }
    else if($(this).width() < 769)
    {
        $(this).tabletFunc(opt.tablet);
    }
    else
    {
        $(this).desktopFunc(opt.desktop);
    }
}

$.fn.phoneFunc = function(str)
{
    $('body').css('background-color', str);
};

$.fn.tabletFunc = function(str)
{
    $('body').css('background-color', str);
};

$.fn.desktopFunc = function(str)
{
    $('body').css('background-color', str);
};

How to install less css on Ubuntu

sudo apt install npm
sudo npm install -g less
sudo ln -s /usr/bin/nodejs /usr/bin/node

PHP resize image before base64 encoding

It took me a while to work this out, but it was worth it. base64 encoding can be really useful in presenting and storing images on the web. However you don't want to add a 2000 pixel width base64 encoded image to your database. Here's how to resize the image before it goes in.

<?php
$file = 'mypic.jpg';
$image = imagecreatefromjpeg($file);
$image = imagescale($image , 100);
ob_start();
imagejpeg($image);
$contents = ob_get_contents();
ob_end_clean();
$dataUri = "data:image/jpeg;base64,".base64_encode($contents);
echo '<img src="'.$dataUri.'" />';
?>

Using jQuery FormData to include files when making POST request

In this example I create a form, with a text, and file input field. When I submit the form, contents from all input fields are submitted through the 'FormData' class. The results from the called script are returned to a div. Finally, the fields are then cleared.
<html>
<head>
    <title>jQuery File Upload</title>
</head>
<body>
    <form action="upload.php" method="POST" enctype="multipart/form-data">
        <input type="text" name="myname" />
        <input type="file" name="fileinfo" multiple="" />
        <button type="submit">Submit</button>
    </form>
    <div id="result"></div>
    <script src="https://code.jquery.com/jquery-3.1.0.min.js"></script>
    <script>  
    (function()
    {
        $('form').on('submit', function(e)
        {
            var theDiv = $('div#result');
            var thisForm = $(this);
            var action = thisForm.attr('action');
            var method = thisForm.attr('method');
            $.ajax(
            {
                url: action,
                type: method,
                data: new FormData(this),
                processData: false,
                contentType: false
            }).done(function(datareceived)
            {
                thisForm.find('input, textarea').val('');
                theDiv.html(datareceived);
            });
            e.preventDefault();
        });
    })();
    </script>
</body>
</html>

To test if it works I use upload.php. See
<?php
$str = NULL;
foreach($_FILES as $file)
{
    if(move_uploaded_file($file['tmp_name'], $file['name']) == FALSE)
    {
        $str .= $file['name'].' not uploaded<br />';
    }
}
$str .= '<br />POST items include : <br />';
foreach($_POST as $postitem => $value)
{
    $str .= 'Name : '.$postitem.' Value : '.$value.'<br />';
}
echo $str;
?>

Ratings field within Bootstrap using Font Awesome stars

I looked around for a nice easy rating field using stars. Just like the ones you find on tripAdvisor. All the solutions looked a little CSS or JS heavy and needed images which are more HTTP connections.
So my solution uses only a little CSS, a small amount of jQuery and font-awesome. You'll have to get font-awesome for it to work.
See below.
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <!-- The above 3 meta tags *must* come first in the head; any other head content must come *after* these tags -->
    <title>Font awesome stars</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" integrity="sha384-1q8mTJOASx8j1Au+a5WDVnPi2lkFfwwEAa8hDDdjZlpLegxhjVME1fgjWPGmkzs7" crossorigin="anonymous">
    <link rel="stylesheet" href="font-awesome/css/font-awesome.min.css" />
    <!--[if lt IE 9]>
      <script src="https://oss.maxcdn.com/html5shiv/3.7.2/html5shiv.min.js"></script>
      <script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
    <![endif]-->
    <style>
    .star-selected
    {
      color:pink;
    }
    </style>
  </head>
  <body>
<form method="POST" action="someaction.php">
      <div class="form-group">
        <input type="hidden" name="stars">
        <i class="fa fa-star" aria-hidden="true" value="1"></i>
        <i class="fa fa-star" aria-hidden="true" value="2"></i>
        <i class="fa fa-star" aria-hidden="true" value="3"></i>
        <i class="fa fa-star" aria-hidden="true" value="4"></i>
        <i class="fa fa-star" aria-hidden="true" value="5"></i>
      </div>
      <button type="submit">Submit</button>
    </form>
   
    <!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js" integrity="sha384-0mSbJDEHialfmuBBQP6A4Qrprq5OVfW37PRR3j5ELqxss1yVqOtnepnHVP9aJ7xS" crossorigin="anonymous"></script>
    <script>
    (function()
    {
      var theStars = $('form').find('i');
      $('i').on('click', function()
      {
        theStars.removeClass('star-selected');
        var theStarIclicked = $(this);
        var highVal = theStarIclicked.attr('value');
        theStarIclicked.addClass('star-selected');
        $("input[name='stars']").attr('value',highVal);
        theStars.each(function(i)
        {
          if($(this).attr('value') < highVal)
          {
            $(this).addClass('star-selected');
          }
        });       
        console.log('Star selected '+$("input[name='stars']").attr('value'));
      });
    })();
    </script>
  </body>
</html>