JavaScript for ABAP Programmers - 1/7 Introduction
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JavaScript was originally created as Mocha in 1995 by Brendan Eich at Netscape in 10 days and was renamed LiveScript and then JavaScript to complement Sun Microsystem's Java, though it is not the same as Java. It borrows elements from languages like Scheme and Perl. JavaScript is standardized by ECMA and various JavaScript engines like SpiderMonkey, Chakra, V8, and Nitro execute it client-side in browsers or server-side in implementations like HANA XSJS. The main differences between JavaScript and ABAP are that JavaScript is weakly typed, has lexical scope, treats functions as first-class citizens, uses prototypal inheritance, and allows both imperative and functional programming.
JavaScript for ABAP Programmers - 1/7 Introduction
- 1. JavaScript for ABAP Programmers Introduction Chris Whealy / The RIG
- 2. JavaScript’s Name – And the Resulting Confusion… JavaScript was first developed by Brendan Eich at Netscape in 1995 (in 10 days). Originally this new scripting language was called “Mocha”. When Netscape Navigator 2.0 was shipped in September 1995, the language was renamed to “LiveScript”. However, when Netscape Navigator 2.0B3 was released on December 4th, 1995, Netscape made a joint announcement with Sun Microsystems to the effect that Netscape’s new scripting language would complement Sun Microsystem’s new Web application language Java; therefore, the new scripting language would be called “JavaScript” – and this has caused no end of confusion ever since… The bottom line is simply this… JavaScript is NOT Java! © 2013 SAP AG. All rights reserved. 2
- 3. JavaScript’s Linguistic Heritage Over the course of the language’s development, various conceptual elements have been borrowed from other languages to form what is now called JavaScript. JavaScript © 2013 SAP AG. All rights reserved. 3
- 4. JavaScript’s Linguistic Heritage Over the course of the language’s development, various conceptual elements have been borrowed from other languages to form what is now called JavaScript. JavaScript © 2013 SAP AG. All rights reserved. 4
- 5. JavaScript’s Linguistic Heritage Over the course of the language’s development, various conceptual elements have been borrowed from other languages to form what is now called JavaScript. Scheme JavaScript © 2013 SAP AG. All rights reserved. 5
- 6. JavaScript’s Linguistic Heritage Over the course of the language’s development, various conceptual elements have been borrowed from other languages to form what is now called JavaScript. Scheme JavaScript Perl © 2013 SAP AG. All rights reserved. 6
- 7. JavaScript Standards JavaScript was standardised by the European Computer Manufacturer’s Association (ECMA) in 1997. JavaScript used in browsers is now considered to be only one implementation of the ECMA-262 specification. Edition Date 1 June 1997 2 June 1998 3 December 1999 4 Abandoned 5 December 2009 5.1 June 2011 6 (Harmony) Work in progress 7 Work in progress © 2013 SAP AG. All rights reserved. 7
- 8. JavaScript Runtime Engines In order to execute a JavaScript program, a JavaScript Engine is needed. Multiple implementations of JavaScript engines are available, with the most widely used being: JavaScript Engine Rhino (Mozilla) SpiderMonkey (Mozilla) Chakra (Microsoft) V8 (Google) Nitro (Apple) © 2013 SAP AG. All rights reserved. 8
- 9. JavaScript Runtime: Client Side Implementations Modern JavaScript engines have been designed to run either from within a web browser or as stand alone, server-side execution engines. Browser JavaScript Engine Mozilla Firefox SpiderMonkey (Mozilla) Microsoft Internet Explorer Chakra (Microsoft) Google Chrome V8 (Google) Apple Safari Nitro (Apple) © 2013 SAP AG. All rights reserved. 9
- 10. JavaScript Runtime: Server Side Implementations There are multiple server-side implementations of JavaScript, many of which are based on Mozilla Rhino (Java based). When speed is required however, Mozilla SpiderMonkey or the Google V8 engine are used instead. Server Side Implementation JavaScript Engine SpiderMonkey (Mozilla) HANA XSJS Accessible via Chakra (Microsoft) V8 (Google) Nitro (Apple) © 2013 SAP AG. All rights reserved. 10
- 11. In A Nutshell – The Main Differences Between ABAP & JavaScript Understanding the differences between ABAP and JavaScript is fundamental to transferring your existing programming skills into JavaScript. Some of the main differences are as follows: ABAP JavaScript Strongly typed Weakly typed Syntax similar to COBOL Syntax derived from Java (and C) Block scope Lexical scope No equivalent concept Functions are 1st class citizens OO using class based inheritance OO using referential inheritance Imperative programming Imperative or Functional programming © 2013 SAP AG. All rights reserved. 11