Introduction to Javascript and ECMAScript

Before answering what ECMAScript is, I want to introduce on its birth history.

To understand this concept, please think about the keyboard that you often use on your telephone, Laptop or PC. Although these types of keyboards are different in manufacturer, they still share the same Layout (letter, number , function and Enter keys are all on the same positions). That's because the keyboard manufacturers are complying with the "QWERTY Layout Standard"

Thus, the "standard" can be understood as a "document" declared by a "reputable" organization in a community and requires all relevant products that are born later to comply with the regulations of this document.

Before ECMAScript was born, a Scripting Language Specification was called Mocha, developed byBrendan Eich (A Programming Engineer works inNetcapse). Then, It was changed its name to LiveScript. With the cooperation between Sun Microsystem and Netscape, the LiveScript Specification was changed its name toJavascript and published in May 1995.

In March 2016 the Netscape Navigator browser 2.0 was born to support the Javascript. Then Microsoft released a similar language such as JScript, with the same syntax as Javascript but different in name to avoid copyright matter. The JScript was added toInternet Explorer 3.0 and released in August 1996. Some things were added to JScript but there were not on Javascript , for example, ActiveX. But basically, in the first time, Javascript and JScript were not too different from each other. All things are written by the Javascript will be able to run on the IE browser of the Microsoft.

With the emergence of JScript, developers face a challenge, because JScript and Javascript are created by two different companies. They will be more different over time when new versions are born. Then the code of developer can run on the Netscape browser but can not run on IE and vice versa.

Netscape has submitted Javascript to ECMA International to standardize and write specification and a duty named ECMA-262 starting in November 1996. And the ECMAScript name was fromed herefrom with agreement among the companies participating in the standardization process. Thus, starting here the two languages such as Javascript and JScript (of 2 different companies) will be developed in compliance with the ECMAScript specification.

In June 2015, ECMA International announced the ES6 version (It is also commonly known as ECMAScript6, ES2015, ECMAScript2015). It is an important upgrade for ECMAScript since ES5 standardized in 2009.

Javascript Engine means a program that reads JavaScript code snippets written and executed by the programmers. They are also often known as Javascript Interpreter. This program is included in the browser like Firefox, Chrome, ...

List of common Script-Engines:

Looking at the above list, you find that most browsers use Javascript Engine. Only IE uses JScript Engine.

Whenever a new specification version of ECMAScript is published, it takes some time so that:

1. The languages such as Javascript, JScript are upgraded based on the new specification.
2. Browsers upgrade their Script-Engine.
3. Developers study and write code in accordance with new standards. Of course, the old standards still exist and are still understood by the Script-Engines.

In fact, when a new version of ECMAScript is announced, Script-Engine developing companies often do not update all new features at once, only updating gradually on a schedule. So programmers often ask questions:

• Which version ECMAScript does this browser support?
• What features of ECMAScript does this browser support ?
• ...

To answer the above questions, you can look up the following link:

The ES5 (ECMAScript 5) specification was born in 2009. Most browsers at present fully support all its features while the ES6(ECMAScript 6) specification was born in 2015. Its browsers have not fully supported all new features. But the ES6 syntax and features are really modern and pure for developers, and they want to use it. The problem is that when writing code with ES6 syntax, this code may not be understood in some browsers.

Transpiler stands for TRANSforming + comPILER. It implies the tools capable of converting code from X version to Y version.

Babel means a Transpiler. It can convert ES6 code to ES5 code. Therefore, developers can write code in the ES6 style and feel assured that it can be executed on all browsers with the help of Babel.