Calculating colour contrast from hex colour code (php, javascript)

This time I have a nice little snippet to offer you: there is an easy way of calculating contrast from hex colour codes. I needed this on one of my web apps where I wanted to display the background of certain buttons in one colour and wanted the app to automatically calculate if I should set black or white as foreground colour for the button so it's easy to read.

Prevent form reload (login, shopping cart... etc).

Today I was looking through my draft posts and saw this one about preventing form reload, and this is the note I took at the time: "set session variable to empty at form load, set it to something at successful submit, if session variable set when submit clicked, throw error" - well, yes, that was the first thought about it I found on the net, however, after I continued to look, I found that there is a better, more efficient way to do this:

Even or odd number validation with PHP

The other day, while I was writing up some PHP code, I ran into a really cool way of identifying if a number is even or odd (refer to the link further down below). I needed it as I looped the creation of a couple of divs and wanted the odd numbered ones to be floated left, the evens to the right.

HTML and PHP includes

I know it's been a long time since I wrote here, but [replace with usual bla-bla], so let me make it up to you guys and give you a nice little hint here.

Usually when I want to build a website quickly and where design or dynamism is not all that important, I use simple HTML instead of PHP as I found it being much quicker to write. However, not being dynamic, a website built in HTML would be very complicated and time consuming to apply any changes to, unless you use a website builder software

Embed music with dowload.php file

Scenario: you would like to embed a music file (.mp3 in our example) into your website and also want to make sure that when someone clicks the download link the usual open / save as window opens instead of the browser trying to open the file directly with whatever plugin already installed.

My solution: we'll have to break this down into two parts: one will be the embed script and the other one will be the download link.