Configure host in Windows VirtualBox to reach local webserver

If you are developing a website on Linux or Mac you may want to check the behavior of the website in Windows with the Internet Explorer or with the latest Microsoft Edge web browser. I am developing the most projects local in a Docker container, a Vagrant box or for example on a local Apache server. Sometimes also with the build in webserver of PHP or grunt-contrib-connect. The type of local webserver is not that important, more important is the fact that the webserver is not reachable from outside. Developing on my Linux machine and switching to an Windows machine in my network to check the behavior of the website is no option as workflow. Luckily is Microsoft providing Free Virtual Machines from IE8 to MS Edge.

Continue reading

Run different php-cli versions with Docker

I am working on a small PHP library that should use some new features from PHP 7, for example scalar type declarations and return type declarations. But my current Debian 8 has only PHP 5.6.29 for me at the moment. The unstable distribution sid is no option to me and in general I try to avoid installing a specific PHP interpreter on my OS. Fortunately I need PHP only on the command line to test my library so I can use Docker to switch between the versions.

Continue reading

Inaccurate rounding with decimal digits

I made a small post about Inexact rounding up or down with decimal digits. But it is also possible to run into the same bug when rounding floating point numbers to the next number with restricted decimal digits. A really common example is the price calculation. You have the price 1.99 for example and the tax is maybe 19%. The resulting price with tax would be 2.3681. So you will need to round the price with two decimal digits to 2.37.

Continue reading

Responsive embedded D3 SVG

The most D3 examples that I can find are not responsive embedded SVG. I guess the main reason for that is not to confuse the reader of a tutorial with stuff outside of D3. With the help of How to Scale SVG from Amelia Bellamy-Royds I would like to show on a minimal D3 example how to make the resulting SVG responsive.

Continue reading

Inexact rounding up or down with decimal digits

Calculations with floating point numbers are often producing small hidden bugs in some programming languages. For example rounding down or up with decimal digits. I want to show on some small examples in Java, JavaScript, Python and C the main problem.

Continue reading

MathJax - Mathematical expressions via JavaScript

MathJax is a JavaScript engine to display mathematical expressions in web browsers. I would have needed in it some posts before on my blog, but I have never tried. Today I would like to show how easy I have integrated in my blog.

Continue reading

CSS conflict between Bootstrap 4 and Prism

Bootstrap 4.0.0-alpha.5 is styling the class .tag and this leads to a CSS conflict with the Prism syntax highlighter. Here my fix to solve this conflict.

Continue reading

Upgrade from Bootstrap version 3 to 4

Bootstrap 4.0.0 seems to be released soon. My small blog is mostly based on plain Bootstrap with a few color changes. I will try to upgrade from Bootstrap 3.3.6 to version v4.0.0-alpha.5. This post will just document the changes that I have noticed while upgrading.

Continue reading

QUnit with Grunt - A minimal JavaScript unittest example

Writing testable JavaScript code is in my eyes sometimes more complex as writing testable code in other programming languages. JavaScript has it roots in the web development and the normal environment for JavaScript code was the web browser. There was always the global document object. Node.js has changed this assumption.

Continue reading

ImageMagick - Resize all images in a directory

I need to resize all images in a directory. The convert command from ImageMagick combined with a loop over all image files in a directory seems to be a good solution.

Continue reading

Newer Older