intro

Eloquent Javascript: Intro – What is Javascript? ;Rough Notes

Resource: Eloquent Javascript, 2nd Edition by Marijn Haverbeke

What is Javascript?

  •  JavaScript (henceforth JS) created in 1995 to add programs to web pages in the Netscape Navigator browser
  • Major graphical web browsers have since adopted JS
  • JS has made modern web applications possible
  • “Modern web applications = applications with which you can interact directly without doing a reload for every action”
  • Also used in websites to provide interactivity

NB: Netscape – a series of web browsers produced by Netscape Communications Corporation (now a subsidiary of AOL); original browser once the dominant browser in terms of usage share (proportion of visitors to web sites that use a certain web browser), but lost to Internet Explorer in the first browser war (competition for dominance in the usage share of web browsers) (first war — Microsoft’s Internet Explorer vs. Netscape’s Navigator)
—Wikipedia: Netscape (web browser)

  • ECMAScript standard : a standard document that describes the way JS should work to ensure that software claiming to support JS really does support JS ; named after Ecma International, the organization that did the standardization
  • ECMAScript and JS can be used interchangeably (two names for the same language)

Disadvantages of JS

  • JS is “ridiculously liberal in what it allows” — almost any command is accepted, but is then interpreted differently
  • Idea behind this design: make programming in JS easier for beginners
  • Reality: Makes finding program errors harder because the system will not point them out to you

Advantages of JS

  • Flexibility allows for many techniques that are impossible in more rigid languages

Different versions

  • Version 3 — widely supported version btwn ~ 2000-2010, the time of JS’s ascent to dominance
  • Version 4 — “changing a living, widely used language … turned out to be politically difficult” — work abandoned in 2008
  • Version 5 — came out in 2009
  • Version 5.1 — 2011 — Editorial changes —w3schools
  • Version 6 — 2015 —  Added classes and modules —w3schools
  • Version 7 — 2016 — added exponential operator (**); added Array.prototype.includes –w3schools
  • This book’s edition came out in 2014 so it will focus on Version 5, which all major browsers support; we should focus on using Version 6, which all major browsers are in the process of supporting

 

  • Platforms on which JS is used: Web browsers, databases i.e. MongoDB, CouchDB (use JS as their scripting and query language)
  • Several platforms for desktop and server programming i.e. notably, Node.js, provides a powerful environment for programming JS outside of the browser