Understanding JavaScript and ECMAScript
What is JavaScript?
JavaScript is an interpreted client-side scripting language developed by Netscape in 1996. Initially, JavaScript was created to manipulate HTML elements, validate user input on the client side and communicate with the server-side code.
Initially, JavaScript can only be run in a Browser. Also, it was known as a scripting language since to execute JavaScript you don’t need to install any SDK or setup any compiler. It can run on a web page with HTML using <script> tag after the web page loads in the browser.
Today, JavaScript is a programming language which you can be used in place of C#, Java, Php or any other object-oriented languages. JavaScript can run in a browser, server-side or on any device using a program known as JavaScript Engine. Some of the most popular JavaScript engines are:
· Chrome V8 — Used in Chrome and Opera browser. Also, used by the Node.js to run JavaScript outside the browser.
· Chakra — Used in IE.
· SpiderMonkey — Used in Firefox.
· JavaScriptCore (Nitro) — Used in Safari.
JavaScript Features
· A dynamic language, so there is no type-checking at compile time.
· A case-sensitive language.
· Interpreted in the browser at the client side.
· Compiled on the server side if it is used with Node.js.
· Single-threaded.
· Platform independent and event-driven language.
JavaScript Usages
· Used to build web applications. The most popular JavaScript-based frameworks are React, AngularJS and Vue.js.
· Used to build server-side applications using Node.js and its frameworks like Express, Koa, Hapi etc.
· Used to build cross-platform mobile apps. The most popular JavaScript-based mobile app development frameworks are Ionic, React Native and Native Script.
JavaScript Client-side Issues
· Client-Side Security Issues like Cross-Site Scripting or XSS attack and Cross-Site Request Forgery (CSRF) attack.
· Client-side JavaScript can be disabled from the browser, which might stop the execution of code.
Each browser supports a different set of objects to manipulate the browser window. Hence it behaves differently in each browser.
What is ECMAScript?
ECMAScript(ES) is a scripting language specification developed by Ecma International to standardize JS in 1997. This standard is widely followed by client-side scripting languages like JavaScript, JScript and ActionScript.
The latest version of JavaScript was 1.8.5 which is equivalent to ECMAScript 5. Now, Form ECMAScript 2015 (ES6) it has become the official name of the JavaScript language.
ECMAScript Version History?
Browser Support
ES3 is fully supported in all browsers; even in old browsers. Also, ES5 is fully supported in all modern browsers. ES6 is not supported by the Internet Explorer but it is supported in all modern browsers such as Chrome, Edge, Firefox, Opera and Safari. ES7 is only supported in Chrome and Opera. The support of ES8 and ES9 is in progress.
So, it is advised to use the ES5 only for the JavaScript front-end development.
