Category: Programming

In JavaScript, we have a native error constructor function which we can create instances of it by using the “new” keyword”. the instance itself doesn’t do anything but by using the “throw” keyword with the error instance, interesting things can happen.

Object Oriented Programing means bringing together the data and the behavior in a single location called an object. data and behavior are the 2 main things in programs. data means the things we keep in memory and behavior means functions, the things that programs can do. This paradigm is entirely different than the functional programming paradigm that keeps a separation between the data and behavior.

Inheritance is when one object gets access to the properties and methods of another object. the classical inheritance is very verbose but the Prototypal inheritance is simple, flexible, extensible, and easy to understand. both ways are not perfect but prototypal inheritance can be very powerful.

Javascript is single-threaded, only one statement is executed at a time. If something in our code is a long process it will freeze our application (block the thread) until it finishes. But as I explained in my previous articles, JavaScript does not work alone in the browser, we have the web API which is a set of features that help us run code asynchronously, a code that runs with callbacks in the background and does not freeze our application.

Modules are highly self-contained and they are grouped with their specific functionality. It’s allowing them to be moved around and used by other places and even to be removed without disrupting the system as a whole.

Functional programming is all about separation of concern which object-oriented programing does as well. but in functional programming, we don’t combine the data and functions in one piece or one object like with object-oriented programming. the functions operate on well-defined data structures like arrays and objects rather than belonging to the data structure like an object.

When The JavaScript engine makes sure that the function has access to all the variables outside of the function, it’s a closure. closures are a feature in JavaScript also called lexical scoping. it’s a combination of 2 things: functions are first-class citizens and the lexical scope.

There are times that we need to change the context of the ‘this’ keyword. since functions are objects and they have properties, we can set them and access them. with ‘call’, ‘apply’ and ‘bind’ we can change the ‘this’ keyword, and we can change the context in which the function is invoked.

The JavaScript engine and the JavaScript runtime are responsible for running JavaScript code, the JavaScript engine alone will freeze the page as long as the call stack is not empty. it means that the JavaScript engine is synchronous. but with the JavaScript runtime, we can run asynchronous code.

The JavaScript runtime is a set of features that exists in the browser and while the JavaScript engine runs our code synchronously, the browser works in the background.