JavaScript Constructor, operator “new”
The regular {…} syntax allows to create one object. But often we need to create many similar objects, like multiple users or menu items and so on. […]
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JavaScript Object methods, “this”
Objects are usually created to represent entities of the real world, like users, orders and so on: And, in the real world, a user can act: […]
JavaScript Garbage collection
Memory management in JavaScript is performed automatically and invisibly to us. We create primitives, objects, functions… All that takes memory. What happens when something is […]
JavaScript Object references and copying
1. Overview One of the fundamental differences of objects versus primitives is that objects are stored and copied “by reference”, whereas primitive values: strings, numbers, […]
JavaScript Objects
As we know from the chapter Data types, there are eight data types in JavaScript. Seven of them are called “primitive”, because their values contain only […]
JavaScript Polyfills and transpilers
The JavaScript language steadily evolves. New proposals to the language appear regularly, they are analyzed and, if considered worthy, are appended to the list at ecma262 and […]
JavaScript Automated testing with Mocha
Automated testing will be used in further tasks, and it’s also widely used in real projects. 1. Why do we need tests? When we write […]
JavaScript Ninja code
Learning without thought is labor lost; thought without learning is perilous. Programmer ninjas of the past used these tricks to sharpen the mind of code […]
JavaScript Comments
As we know from the chapter Code structure, comments can be single-line: starting with // and multiline: /* … */. We normally use them to describe how and why […]
JavaScript Coding Style
Our code must be as clean and easy to read as possible. That is actually the art of programming – to take a complex task […]
JavaScript Debugging in the browser
Before writing more complex code, let’s talk about debugging. Debugging is the process of finding and fixing errors within a script. All modern browsers and most […]
JavaScript specials
This chapter briefly recaps the features of JavaScript that we’ve learned by now, paying special attention to subtle moments. 1. Code structure Statements are delimited […]
JavaScript Arrow functions, the basics
1. Overview There’s another very simple and concise syntax for creating functions, that’s often better than Function Expressions. It’s called “arrow functions”, because it looks […]
JavaScript Function expressions
1. Overview In JavaScript, a function is not a “magical language structure”, but a special kind of value. The syntax that we used before is […]
JavaScript Functions
Quite often we need to perform a similar action in many places of the script. For example, we need to show a nice-looking message when […]
JavaScript The “switch” statement
A switch statement can replace multiple if checks. It gives a more descriptive way to compare a value with multiple variants. 1. The syntax The switch has one or more case blocks and […]
JavaScript Loops: while and for
We often need to repeat actions. For example, outputting goods from a list one after another or just running the same code for each number […]
JavaScript Nullish coalescing operator ‘??’
1. Overview A recent additionThis is a recent addition to the language. Old browsers may need polyfills. The nullish coalescing operator is written as two […]
JavaScript Logical operators
There are four logical operators in JavaScript: || (OR), && (AND), ! (NOT), ?? (Nullish Coalescing). Here we cover the first three, the ?? operator is in the next article. Although they are called “logical”, […]
JavaScript Conditional branching: if, ‘?’
Sometimes, we need to perform different actions based on different conditions. To do that, we can use the if statement and the conditional operator ?, that’s also called […]
