JavaScript Global object
1. Overview The global object provides variables and functions that are available anywhere. By default, those that are built into the language or the environment. […]
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JavaScript The old “var”
This article is for understanding old scripts The information in this article is useful for understanding old scripts. That’s not how we write a new […]
JavaScript Variable scope, closure
JavaScript is a very function-oriented language. It gives us a lot of freedom. A function can be created at any moment, passed as an argument […]
JavaScript Rest parameters and spread syntax
Many JavaScript built-in functions support an arbitrary number of arguments. For instance: Math.max(arg1, arg2, …, argN) – returns the greatest of the arguments. Object.assign(dest, src1, …, […]
JavaScript Recursion and stack
Let’s return to functions and study them more in-depth. Our first topic will be recursion. If you are not new to programming, then it is probably […]
JavaScript JSON methods, toJSON
Let’s say we have a complex object, and we’d like to convert it into a string, to send it over a network, or just to […]
JavaScript Date and time
Let’s meet a new built-in object: Date. It stores the date, time and provides methods for date/time management. For instance, we can use it to store […]
JavaScript Destructuring assignment
The two most used data structures in JavaScript are Object and Array. Objects allow us to create a single entity that stores data items by key. Arrays allow […]
JavaScript Object.keys, values, entries
Let’s step away from the individual data structures and talk about the iterations over them. In the previous chapter we saw methods map.keys(), map.values(), map.entries(). These methods are […]
JavaScript WeakMap and WeakSet
1. Overview As we know from the chapter Garbage collection, JavaScript engine keeps a value in memory while it is “reachable” and can potentially be used. […]
JavaScript Map and Set
Till now, we’ve learned about the following complex data structures: Objects are used for storing keyed collections. Arrays are used for storing ordered collections. But […]
JavaScript Iterables
Iterable objects are a generalization of arrays. That’s a concept that allows us to make any object useable in a for..of loop. Of course, Arrays are iterable. But […]
JavaScript Array methods
Arrays provide a lot of methods. To make things easier, in this chapter they are split into groups. 1. Add/remove items We already know methods […]
JavaScript Arrays
Objects allow you to store keyed collections of values. That’s fine. But quite often we find that we need an ordered collection, where we have a […]
JavaScript Strings
In JavaScript, the textual data is stored as strings. There is no separate type for a single character. The internal format for strings is always UTF-16, […]
JavaScript Numbers
In modern JavaScript, there are two types of numbers: Regular numbers in JavaScript are stored in 64-bit format IEEE-754, also known as “double precision floating point […]
JavaScript Methods of primitives
1. Overview JavaScript allows us to work with primitives (strings, numbers, etc.) as if they were objects. They also provide methods to call as such. […]
JavaScript Object to primitive conversion
What happens when objects are added obj1 + obj2, subtracted obj1 – obj2 or printed using alert(obj)? JavaScript doesn’t exactly allow to customize how operators work on objects. Unlike […]
JavaScript Symbol type
By specification, object property keys may be either of string type, or of symbol type. Not numbers, not booleans, only strings or symbols, these two […]
JavaScript Optional chaining ‘?.’
A recent additionThis is a recent addition to the language. Old browsers may need polyfills. The optional chaining ?. is a safe way to access nested object […]
