An Introduction to JavaScript
If you’re a web developer, chances are you’ve run into the term “javascript” in some capacity. Whether you’re working with HTML or CSS, JavaScript allows websites to update and interact with the user, without reloading the entire page. It’s an interpreted language that runs directly inside of the browser and, as a result, requires much less computing power than other compiled languages.
It’s used in modern web applications to provide features like dynamic content, data validation and Ajax functionality. You probably see it in action every day when a Facebook timeline updates automatically on your screen or Google suggests search terms after you start typing. But how does it work? This article gives you a quick introduction to the inner workings of javascript, so that when you look at your code, you’ll know exactly what’s happening behind the scenes.
JavaScript is a procedural, object-oriented programming language. It uses function definitions and a call-by-value model to control how programs are executed. Its structure is relatively simple, making it easier to read and understand than many other programming languages. It also compiles at runtime, meaning it doesn’t require a separate compiler and is usually faster than other interpreted languages.
Variables are key elements in a JavaScript program. They can store values such as numbers, names or product ID codes. They can also store strings of characters, such as words or sentences. Like other programming languages, JavaScript supports different types of data and performs basic operations on it such as adding, subtracting, multiplying and dividing. It can also perform logical operations, such as comparisons and boolean value functions.
Like other languages, javascript contains a variety of loops and operators to handle iteration. These include for loops, which iterate over iterables such as arrays, and for…in loops that iterate over enumerable properties of objects. It also has a switch statement that lets you branch based on equality checks. In addition, javascript has a number of boolean functions that return the truth or false.
Other important language capabilities include recursion, which allows you to define a function within another, and named functions, which are more easily identifiable when debugging. The function name is displayed as part of the function’s local scope and shows up in stack traces, for example. It is also possible to create nested functions, which are functions defined inside of other functions. These are known as IIFEs (Inner Function Foreach) and can be invoked in the same way as outer functions.
There are also a number of special keywords that provide additional capabilities. These include var, const, for, while, and others. Additionally, javascript supports the use of Unicode characters in identifiers and uses a special notation for string literals. The language also supports a number of math functions, including binary, hex, and octal number conversions.
The language is fairly concise and uses punctuation similar to other scripting languages, such as Python. Single line comments are indicated by a double forward slash (//) and multi-line comments are marked with /* and */.