JavaScript started as a language for the Netscape Navigator browser in 1995. It has since been adopted to every web browser today. Although primarily being deployed as a scripting language for the World Wide Web, JavaScript is a fully functional programming language. It is very easy to learn and there are many other technologies, beyond web developing, that can be integrated alongside JavaScript.

While it is powerful and complicated, but what makes JavaScript so popular is mainly due to the fact that it is supported by every web browser out there today. While HTML lays out the skeleton for a web page and CSS puts down the styling rules for its graphical display, JavaScript adds user interactivity to it. It is also the only free, cross-platform, client-side programming language that is universally adopted.

With JavaScript, it is easy for a user to enter data onto a web page and see the result. Think of every intractable application on a web page. They are all made possible thanks to JavaScript. For example, it has the ability to catch both mouse and keyboard inputs and allow the developers to connect those inputs to the certain interactions on the web page. Thus, the ability to interact with an web application with a few clicks of your mouse or some keystrokes from your keyboard is given birth by the use of JavaScript.

JavaScript is powerful and complicated, and yet, like any other programming languages, it has its limitations and flaws. One major limitation is that it cannot access anything outside the web page itself. This is done for the reason of security that web pages can’t install files onto your computer, but it also means that you can’t use JavaScript to read or write files. One of the flaws comes from it being cross-platform. Different browsers interpret JavaScript differently. This may lead to inconsistencies in applications across platforms. Another flaw comes from the idea to make JavaScript easy for beginners to learn, letting it to be very liberal in what it allows. For example, you could perform an arithmetic operation on a null value and an integer without raising an error. The system will not point out this error since JavaScript allows such operation with its type coercion and it will make catching errors difficult. JavaScript’s type coercion evaluates two operands of different types and changes one operand to a type that it deems “equivalent” to the other. The outcome of such operation in JavaScript isn’t always what you expected and is prone to errors.