When creating interactive web pages, developers often need to execute some actions when a given event occurs. Changing the image of a carousel when a user clicks on one of its arrows, showing a tooltip when a word is hovered, or validating a field when a user moves the focus onto another field are common examples. To execute these actions, we have to add event listeners to the elements of the page.
In this article, I’ll explain what event listeners are, and how to add and remove them from a web page. I’ll show several examples and talk about patterns to avoid when dealing with event listeners. The topic will be discussed in depth. So, even if you’re an expert, you might not know some of the details covered.
When working on a project, we often use libraries that implement methods that aren’t built-in in the programming language in use but we need. These libraries don’t cover all the possible methods, so they might lack one or more crucial features we need. When this happens, we have two choices: the first is to create our own module that implements the methods we need, the second is to add those methods to the library itself or the built-in classes of the language. The latter is known as Monkey patching.
In this article, we’ll look at what Monkey patching is, what pros and cons it has, and also a couple of examples that employ this technique.
HTML5 introduced several new elements to address many common use cases that developers have faced over the years. As an example you can think to the new audio and video elements that allow you to avoid the use of third-party software like Flash and Silverlight to play audios and videos. While media streams play an important role on the web, the W3C and the WHATWG have also tried to enhance the semantic of web pages. One of these new elements is the time element.