Overview

JavaScript is a programming language that was created by Brendan Eich in 1995 for adding interactivity to web pages. Initially it was called LiveScript, but later it was renamed to JavaScript.

It runs in the browser and on the server. JavaScript is a dynamic, weakly typed, and interpreted programming language. It is a multi-paradigm language, which means that it supports different programming styles like object-oriented, functional, and imperative programming.

Before jumping to the next thing about JS, let's see what programming language is

Programming Language

A programming language is a set of rules, symbols, and syntax that is used to communicate instructions to a computer. It is a way for humans to write programs that the computer can execute. There are many programming languages, each with its own set of rules and syntax. Some examples of programming languages include:

Uses of JavaScript

JavaScript is a programming language that is commonly used in software development in several contexts. Here are some examples of how JavaScript is used in different areas of software development like frontend, backend, mobile, desktop, game development, etc.

History and evolution of JavaScript

JavaScript is a programming language that was created by Brendan Eich in 1995 for adding interactivity to web pages. Initially it was called LiveScript, but later it was renamed to JavaScript. ECMAScript (shortly ES) is the official name of the JavaScript standard. It is maintained by the European Computer Manufacturers Association (ECMA) and is the standard that all JavaScript engines must follow.

JavaScript has undergone several versions over the years. The most widely used versions are:

• ES1 - also known as ECMAScript 1, released in 1997
• ES2 - 1998
• ES3 - 1999
• ES5 - 2009
• ES6 - 2015
• ES7 - 2016
• ES8 - 2017
• ES9 - 2018
• ES10 - 2019
• ES11 - 2020
• ES12 - 2021

Let's see them in details.

ES1 - 1997

Introduced the basic syntax of the language, including variables, operators, and control statements.

ES2 - 1998

Introduced the with statement, which allows you to create a new scope for a block of code. It also introduced the for-in loop, which allows you to iterate over the properties of an object.

ES3 - 1999

Introduced regular expressions, better string handling, new control statements, and try-catch exception handling. It also improved the handling of errors and introduced the strict mode, which helps to prevent some common JavaScript errors.

ES5 - 2009

Made improvements to the language such as better support for arrays, new methods for working with strings and objects, and the ability to create more efficient code using strict mode. It also introduced new methods to help prevent and fix common coding mistakes.

ES6 - 2015

ES6 is a significant update to the language, introducing many new features and improvements. Some notable features include:

• let and const for variable declarations - to declare variables that are block-scoped
• arrow functions - a shorter syntax for writing functions i.e. const add = (a, b) => a + b
• template literals - backticks (``) for string interpolation and multi-line strings
• classes and inheritance - a way to create objects and classes
• destructuring assignment - to unpack values from arrays and objects into distinct variables
• default function parameters - to set default values for function parameters
• Promises for handling asynchronous code - a more readable way to handle asynchronous code
• and many more improvements and additions to the language

ES7 - 2016

ES7 introduced several new features, including:

• Array.prototype.includes() - method to check if an array contains a value or not i.e. array.includes(value) returns true if the array contains the value, and false if it does not
• Exponentiation operator (**) - to calculate the power of a number (e.g. 2 ** 3 is 8)
• and async/await - another way to handle asynchronous code
• and many more improvements and additions to the language

ES8 - 2017

It includes:

• Object.values() and Object.entries() - methods to get the values and entries of an object as an array (e.g. Object.values({ name: 'John', age: 30 }) returns ['John', 30])
• String padding - to add padding to a string using the padStart() and padEnd() methods (e.g. 'hello'.padStart(10) returns ' hello')
• Object.getOwnPropertyDescriptors() - method to get the descriptors of an object
• async functions - asynchronous functions that return a Promise and can use the await keyword
• and more improvements and additions to the language

ES9 - 2018

It introduced:

• Asynchronous iteration - to iterate over asynchronous data i.e. for await (const value of asyncIterable) { ... }
• rest/spread properties for objects - to copy objects and merge objects using the spread operator (...) i.e. { ...obj1, ...obj2 }
• promise.finally() - to execute code after a Promise is settled (either fulfilled or rejected)
• template literals improvements - to use raw strings and to tag template literals
• and many others

ES10 - 2019

It included:

• Array.flat() and Array.flatMap() - to flatten arrays and to flatten arrays and map them at the same time
• Object.fromEntries() - to convert an array of key-value pairs into an object i.e. Object.fromEntries([['foo', 1], ['bar', 2]]) // {foo: 1, bar: 2}
• String.trimStart() and String.trimEnd() - to trim whitespace from the beginning and end of a string
• and others

ES11 - 2020

It introduced:

• Dynamic import() - to import modules dynamically (i.e. at runtime)
• globalThis - to get the global object i.e. globalThis is the same as window in the browser and global in Node.js
• Nullish coalescing operator (??) - to return the right-hand side operand when the left-hand side operand is null or undefined
• BigInt - to represent integers larger than 2^53 - 1 which is the largest number JavaScript can reliably represent with the Number primitive and represented by the Number.MAX_SAFE_INTEGER constant
• and others

ES12 - 2021

It includes:

• Logical assignment operators - to assign values to variables based on a condition (e.g. x ||= y is the same as x = x || y)
• Optional chaining operator (?.) - to access properties of nested objects without having to check if the parent object exists or not
• Nullish coalescing operator (??) - to return the right-hand side operand when the left-hand side operand is null or undefined
• String.prototype.matchAll() - to get all matches of a regular expression in a string as an iterator of RegExpMatchArray objects (i.e. string.matchAll(/foo/g))
• JSON superset - to allow trailing commas in JSON objects and arrays and to allow single quotes in JSON strings (i.e. {"foo": "bar",} and {"foo": 'bar'} are valid JSON)
• and others

It's worth noting that not all browsers or JavaScript engines support the latest version of ECMAScript, so it's important to keep that in mind when developing applications that need to run on multiple platforms, because some features may not be supported on all browsers, like Internet Explorer.