A (Re)-Introduction to JavaScript - The Diigo Meta page

• 18 Jun 17
  

  kevino

  empty

• 14 Aug 14
  

  John Barbieri

  Imported

• 27 Sep 11
  

  Flash D

  javascript programming pre-diigo

• 27 Apr 11
  

  quartzo

  javascript tutorials Imported from del.icio.us

• 26 Jan 11
  

  Victor Cox

  ajax

• 22 Jun 10
  

  Pedro Ângelo

  None

  javascript

• 21 Jan 09
  

  petter w

  Another good introduction to JavaScript. Written in a slightly different way. Might work better for some.

  javascript tutorial development technology

• 30 Dec 08
  

  Lee Aylett

  Web Development Javascript

• 13 Oct 08
  

  Brian Hannah

  programming javascript tutorial web webdesign reference development tutorials tips code js scripting webdevelopment

• 10 Sep 08
  

  Nightowl Nightowl

  javascript webdesign reference touchup!!

• 09 Sep 08
  

  chalda

  Clanek o syntaxy javascriptu - je tu zminka i o "custom objects", pro me tedy puvodne anonymnich polich :) Dobre shrnuti a opacko, jak na js.

  javascript tutorial

• 

  Bjoern Stierand

  javascript programming tutorial

• 04 Sep 08
  

  Robert Wallace

  javascript delicious

• 17 Jul 08
  

  Julian Knight

  Nice summary of programming with JS. Assumes a basic programming knowledge so is especially useful for people converting from other languages.

  javascript programming reference scripting

  • • The comments on && and || using short-circuits and the resultant examples are particularly nice.
    Add Sticky Note

  • The && and || operators use short-circuit logic, which means they will execute their second operand dependant on the first. This is useful for checking for null objects before accessing their attributes:

      

    var name = o && o.getName();

      

    Or for setting default values:

      

    var name = otherName || "default";
• 22 May 08
  

  Feng Wuhan

  javascript reference

• 06 May 08
  

  gianninoalvarez

  javascript tutorial

• 08 Apr 08
  

  parthbakshi bakshi

  Javascript

• 26 Mar 08
  

  Roberto Ortelli

  introduction javascript tutorial

• 20 Mar 08
  

  Noel Gomez

  javascript tutorial

• 06 Mar 08
  

  Antonio Delgado

  programming javascript tutorials

• 03 Mar 08
  

  Marcio Barrios

  javascript tutoriales pendiente oop referencia

• 20 Jan 08
  

  Gigel Plancton

  javascript

• 10 Jan 08
  

  mrseoliveira

  del.icio.us imported javascript

• 06 Jan 08
  

  Matt Kelly

  javascript object tricks

• 28 Dec 07
  

  osmanizbat

  javascript

• 15 Nov 07
  

  zeroeth

  really good javascript document

  javascript for:raeson for:ebeard

• 13 Nov 07
  

  ftcistheshit

  javascript cheatsheet closures

• 16 Oct 07
  

  mpavlik

  Development DHTML Javascript Imported Bookmarks

• 

  aka equalium

  javascript js_next_level

• 26 Sep 07
  

  kenwei

  javascript reference tutorials

• 13 Sep 07
  

  aaron r

  javascript tutorial

• 03 Sep 07
  

  dan

  unromantic, practical headsup on the philosophy of javascript's architecture.

  cheatsheet presentation language teachmyself javascript howto

• 13 Jul 07
  

  mrzepka

  javascript reference

• 30 Jun 07
  

  kabs

  javascript

• 06 May 07
  

  rene_kapusta

  js

• 04 May 07
  

  Cari Rottenberg

  help howto javascript web programming

• 03 Apr 07
  

  MadQuark

  Tutorial de Javascript.

  javascript tutorial programming reference help

• 16 Mar 07
  

  rob_cornelius

  javascript tutorial reference

• 15 Mar 07
  

  A Roy

  scripting javascript tutorials reference * imported-110502

• 14 Mar 07
  

  jdyndale

  detailed javascript overview

• 12 Mar 07
  

  Jerry Wong

  javascript tutorial web

• 03 Feb 07
  

  torstenmufgord

  Web Development

• 16 Jan 07
  

  Andre Malheiro

  Notes made in preparation for a three hour tutorial at ETech in San Diego, March 6th 2006

  javascript tutorial programming language

• 09 Dec 06
  

  Effie Nadiv

  javascript tutorial programming closures fromdelicious

• 06 Dec 06
  

  ahrumsong

  imported

• 02 Dec 06
  

  Leandro Rodrigo Saad Cruz

  javascript

• 09 Nov 06
  

  samuel sung

  javascript

• 

  Matti Narkia

  javascript tutorial programming reference tutorials web webdev Prototype popular

• 05 Nov 06
  

  Julien Casanova

  javascript tutorials

• 29 Oct 06
  

  Jamie

  javascript

• 25 Oct 06
  

  Karthik Hariharan

  javascript

• 12 Oct 06
  

  Pierre L

  javascript tutorial

• 09 Oct 06
  

  Kenneth Solberg

  javascript

• 02 Oct 06
  

  Nathan Rodeback

  JavaScript Introduction

  JavaScript Tutorial

• 14 Sep 06
  

  Finn Pröpper

  lang:en cat:webworking javascript tutorials

• 02 Sep 06
  

  Mark Saunders

  javascript

• 

  Lindsay Donaghe

  codesnippets ie javascript memoryleak troubleshooting tutorials

  • An unfortunate side effect of closures is that they make it trivially easy to leak memory in Internet Explorer. JavaScript is a garbage collected language - objects are allocated memory upon their creation and that memory is reclaimed by the browser when no references to an object remain. Objects provided by the host environment are handled by that environment.

      

    Browser hosts need to manage a large number of objects representing the HTML page being presented - the objects of the DOM. It is up to the browser to manage the allocation and recovery of these.

      

    Internet Explorer uses its own garbage collection scheme for this, separate from the mechanism used by JavaScript. It is the interaction between the two that can cause memory leaks.

      

    A memory leak in IE occurs any time a circular reference is formed between a JavaScript object and a native object. Consider the following:

      

    function leakMemory() {     var el = document.getElementById('el');     var o = { 'el': el };     el.o = o; }

      

    The circular reference formed above creates a memory leak; IE will not free the memory used by el and o until the browser is completely restarted.

      

    The above case is likely to go unnoticed; memory leaks only become a real concern in long running applications or applications that leak large amounts of memory due to large data structures or leak patterns within loops.

      

    Leaks are rarely this obvious - often the leaked data structure can have many layers of references, obscuring the circular reference.

      

    Closures make it easy to create a memory leak without meaning to. Consider this:

      

    function addHandler() {     var el = document.getElementById('el');     el.onclick = function() {         this.style.backgroundColor = 'red';     } }

      

    The above code sets up the element to turn red when it is clicked. It also creates a memory leak. Why? Because the reference to el is inadvertently caught in the closure created for the anonymous inner function. This creates a circular reference between a JavaScript object (the function) and a native object (el).

      

    There are a number of workarounds for this problem. The simplest is this:

      

    function addHandler() {     var el = document.getElementById('el');     el.onclick = function() {         this.style.backgroundColor = 'red';     }     el = null; }

      

    This works by breaking the circular reference.

      

    Surprisingly, one trick for breaking circular references introduced by a closure is to add another closure:

      

    function addHandler() {     var clickHandler = function() {         this.style.backgroundColor = 'red';     }     (function() {         var el = document.getElementById('el');         el.onclick = clickHandler;     })(); }

      

    The inner function is executed straight away, and hides its contents from the closure created with clickHandler.

      

    Another good trick for avoiding closures is breaking circular references during the window.onunload event. Many event libraries will do this for you.
• 01 Sep 06
  

  Ken Finnigan

  javascript tutorial programming reference

• 

  e kam
• 

  Steve Shipley

  javascript programming tutorials

• 28 Aug 06
  

  Mac Dillon

  javascript programming

• 14 Aug 06
  

  Jürgen R Plasser

  javascript

• 11 Aug 06
  

  Hardy Heron

  tutorial javascript

• 08 Aug 06
  

  Caspar Van der Linden

  An overview of Javascript explaining ways of doing things in a new (object oriented) manner. Good for oldskool people.

  General WebDev JavaScript

  • Why a re-introduction? Because JavaScript has a reasonable claim to being the world's most misunderstood programming language. While often derided as a toy, beneath its deceptive simplicity lie some powerful language features. The last year has seen the launch of a number of high profile JavaScript applications, showing that deeper knowledge of this technology is an important skill for any web developer.
• 05 Aug 06
  

  Luke Hardiman

  articles code javascript js language programming prototype reference scripting standards tutorial

• 03 Aug 06
  

  Matt Penny

  tools

• 

  dilip pillai

  javascript

• 

  Edward French

  javascript tips types

• 02 Aug 06
  

  David

  system:unfiled

• 

  vivpuri

  javascripts

• 30 Jul 06
  

  Gary Burge

  Notes made in preparation for a three hour tutorial.

  Javascript tutorials

• 09 Jul 06
  

  craig hancock

  javascript toread tutorials

• 21 Jun 06
  

  doubleday

  Flickr slides: http://simon.incutio.com/slides/2006/etech/javascript/js-reintroduction-notes.html

  javascript tutorial

• 03 Jun 06
  

  Fogday Studios

  Why a re-introduction? Because JavaScript has a reasonable claim to being the world's most misunderstood programming language. While often derided as a toy, beneath its deceptive simplicity lie some powerful language features. The last year has seen the l

  javascript

• 31 May 06
  

  Hans Henderson

  "A good, chatty, easy-to-read introduction to JavaScript with enough detail to be practical" jeremyruston

  javascript language reference web_design howto coding

• 

  Jeremy W

  some stuff on circular references at bottom

  javascript

• 30 May 06
  

  AA Barker

  js tutorial

• 28 May 06
  

  Martin Stein

  javascript reference

• 25 May 06
  

  Richard Klein

  javascript tutorial introduction

• 13 May 06
  

  Andrew White

  Why a re-introduction? Because JavaScript has a reasonable claim to being the world's most misunderstood programming language. While often derided as a toy, beneath its deceptive simplicity lie some powerful language features. The last year has seen the l

  javascript

• 27 Apr 06
  

  Rob Crowther

  Javascript Web Development

• 21 Apr 06
  

  Mike Rotenberg

  Webdesign reference programming javascript tutorial development scripting

• 

  Michał Wysoczański

  javascript webdev web

• 18 Apr 06
  

  Colin Simpson

  how-to Javascript internet web design

• 04 Apr 06
  

  Kenneth Priisholm

  JavaScript

• 01 Apr 06
  

  jabbslad

  javascript programming reference toread tutorial

• 29 Mar 06
  

  Matija Grabnar

  ajax

• 

  pvav pvav

  Nejaký ľahký úvod do Javascriptu od Simona Willisona (prednesený ako 3-hodinový tutoriál na ETechu v San Diego - 6. marec 2006).

  prog.javascript

• 

  Dan Phillips
• 28 Mar 06
  

  Vamsee Krishna M

  javascript

• 27 Mar 06
  

  Actual Al

  programming webdev for:hongkongpete

• 

  organised

  javascript learning

• 24 Mar 06
  

  furl_ed55
• 23 Mar 06
  

  Alexander

  javascript tutorial

• 22 Mar 06
  

  Jim Moore

  javascript programming web

• 

  nathan arnold

  Good overview

  development technology webdev programming javascript

• 

  Ben Turner

  imported Webdesign Javascript

• 

  Jean-Marc Fontaine

• 

  Cedric Beust

  javascript

• 

  Thomas Wallace

  JavaScript

Public Stiky Notes

• 
  Julian Knight on 2008-07-17
  The comments on && and || using short-circuits and the resultant examples are particularly nice.

Page Comments

• 
  Gary Burge on 2006-08-02
  Notes made in preparation for a three hour tutorial.
• 
  Luke Hardiman on 2006-08-05
  notes for willison's reintroduction talk / presentation
• 
  Lindsay Donaghe on 2006-09-02
  Good information on how to avoid IE memory leaks if using Javascript closures.

Would you like to comment?

Join Diigo for a free account, or sign in if you are already a member.