A huge amount of software exists in the world, controlling the systems that enrich our lives. Some code is really obvious, such as operating systems like Windows, web sites, and video games. Some is not so obvious, for example the embedded code that controls our microwave, our thermostat, or our car engine.
The exact format, syntax and usage of different types of code differs greatly, but most share fundamental structures and concepts. In this course, we’ll aim to teach you these fundamentals. The particular type of code we’ll use in this course is JavaScript, the programming language that powers many web sites and applications. We’ve chosen this one because it is readily available, and very easy to demonstrate tangible results with, but the aim here is not really to just teach you JavaScript, but to teach you the underlying principles that apply to pretty much every programming language.
What are we doing when we write code?
Regardless of what type of code we write, we write it to control computer systems: this could be because we want to find more information about those systems, give them information/data to process, or give them instructions. In the same way that we can use a language like English, German or Chinese to ask a person questions and give them instructions, we can use a language like JavaScript to ask computers questions and give them instructions.
The computer has to take in this code in some way, read it, and then do something as a result. For the computer to understand the code, it has to be written in the right syntax: the structure of any language is important, for making yourself understood. The syntax of English and other human languages is verbs, nouns, adjectives, etc. The syntax of JavaScript is variables, functions, loops, etc.
The computer will have a piece of software that reads the code you write, works out what to do with it, and then returns a result. This is often called an interpreter, or an engine perhaps. In the case of JavaScript, the interpreter is the web browser you are using. A web browser downloads web pages, interprets the code contained within them (which will usually include some JavaScript), and gives you a web page to look at.
Note on Compilers: Some languages also need a compiler to run: an application that turns code into a package that can then be run to create an output. Flash is an example of a compiled language — you create some Flash source code, then compile it into a Flash Movie. A web browser with the Flash Player plugin installed can then display this Flash movie, which is its own standalone little block; the source code is no longer readable.
Interpreted languages are often easier to learn than compiled languages, because with interpreted languages you can just open up the source code and see how it works. You can’t do that with compiled languages because the language is converted into a non-human readable form when compiled.
Leave a Reply