(public).sospep.subjects ~ view article ~ REVIEW-VIDEO-douglas-crockford-on-javascript-the-good-parts

<h1 style="text-align: center;">Crockford on Javascript: The Good Parts</h1>
<div><ol>
<li>[] about&nbsp;</li>
<ol>
<li>]&nbsp;<a href="person?id=172" target="_blank">douglas crockford</a> - works @paypal, previously @yahoo, js pioneer, defined json standard,&nbsp;</li>
</ol>
<li>[] js is misunderstood&nbsp;</li>
<ol>
<li>] not held in good esteem, there is no love in the js community</li>
<li>] b/c it 'looks familiar', c, java</li>
<li>] led to people using js, without bothering to really trying to 'learn' js</li>
<li>] understandbly this leds to frustration</li>
<li>] knowing what your doing makes a difference</li>
<li>] contains some of the best ideas ever put forward for a programming langauage</li>
<li>] contains some of the worst ideas ever put forward for a programming language</li>
</ol>
<li>[] js is everywhere</li>
<ol>
<li>] it is the 'virtual machine' for the world &nbsp;&nbsp;</li>
<li>] it is the most widely used programming language in the world and ...&nbsp;</li>
<li>] it is used by every level of programmer, from experts to 'cut+pasters'</li>
</ol>
<li>[] js complaints&nbsp;</li>
<ol>
<li>] not a language i know</li>
<ol>
<li>man up and learn the language (if you need to write it)</li>
</ol>
<li>] browser programming experience is awful(DOM),</li>
<ol>
<li>it is, not js fault, fault of the DOM, currently ajax libraries (yui,jquery,...)</li>
</ol>
<li>] its not fast</li>
<ol>
<li>its not, mainly the DOM's fault,&nbsp;</li>
<li>improving with high perf js engines like google v8(chrome),&nbsp;</li>
<li>even though "i dont see it making a difference in web apps for a long time" ???&nbsp;</li>
</ol>
<li>] js is just a big pile of mistakes&nbsp;</li>
<ol>
<li>its NOT just a big pile of mistakes, contains some of the best ideas ever put forward for a programming language, from self(prototypal inheiritance, dynamic objects) from scheme(lambda, loose typing), java (syntax, conventions), perl(regular expressions)</li>
</ol></ol>
<li>[<a href="http://www.youtube.com/watch?v=hQVTIJBZook&amp;feature=player_detailpage#t=694" target="_blank">11:38</a>] js the 'bad' parts&nbsp;</li>
<ol>
<li>] 'global variables'</li>
<ol>
<li>] worst part by far,&nbsp;</li>
<li>] for linkage, js doenst have a 'linker' so the way 'compilation units' get bound together is they will get tossed upon a 'common global namespace' where all the variable names can collide and interfere with each other, leads to reliability problems, security problems, XSS attacks fundamentally enabled by the use of global variables</li>
</ol>
<li>] '+' operator - adds and concatenates,&nbsp;</li>
<ol>
<li>] BUT you cant 'predict' what its going to do, common source of errors</li>
</ol>
<li>] automatic semi-colon insertion&nbsp;</li>
<ol>
<li>] use style - 'brackets on the right', this style is required because of the languages automatice semi colon insertion, if the compiler finds an error, it backs up and inserts a semi colon where it thinks it should be, reccommends you learn where the semi colons go and put them there</li>
</ol>
<li>] typeof&nbsp;</li>
<ol>
<li>] used for testing what type your object is, but in js everything is an object so it often useless because array = object, null = object , etc&nbsp;</li>
</ol>
<li>] with&nbsp;</li>
<ol>
<li>] doesnt work right, causes programs to be slower just because its in the language, recommends you avoid using it</li>
</ol>
<li>] eval&nbsp;</li>
<ol>
<li>] most mis used feature in the language, shouldnt need to use it</li>
</ol>
<li>] phony arrays</li>
<ol>
<li>] in js arrarys are essentially hashtables, keys are turned into strings and then hashed to locate the buckets, performance penalty BUT its easier because you dont have to dimension arrays</li>
</ol>
<li>]&nbsp;'==' and '!=='&nbsp;</li>
<ol>
<li>] equality operator that does type conversion, problematic,&nbsp;</li>
<li>] transitivity examples slide</li>
<li>] "===" the triple equals operater DOES NOT do type conversion, recommends using that exclusively</li>
</ol>
<li>] false, null, undefined, NAN</li>
<ol>
<li>] too many bottom values, several things that mean almost the same but are slightly different in their meaning</li>
</ol>
<li>] dynamic objects&nbsp;</li>
<ol>
<li>] 2 errors can cancel each other out&nbsp;</li>
</ol>
<li>] good features that interact badly&nbsp;</li>
<ol>
<li>objects can inheirit from other objects - ??</li>
<li>functions can be members of objects - ??</li>
<li>for in statement - mixes inhierited functions with the desired data members, &nbsp;not useful, common source of errors, designed to do 'deep dredge' vs 'shallow skim', does deep but lots of confusion about how to use</li>
</ol>
<li>] more 'bad heritage' (goes back to c syntax)</li>
<ol>
<li>blockless statements - statements without the curly braces</li>
<li>expression statments -&nbsp;</li>
<li>floating point arithmetic -&nbsp;</li>
<li>switch statments - can fall through</li>
</ol>
<li>+*] new&nbsp;</li>
<ol>
<li>] &nbsp;</li>
</ol></ol>
<li>[<a href="http://www.youtube.com/watch?v=hQVTIJBZook&amp;feature=player_detailpage#t=1356" target="_blank">22:36</a>] js the 'good' parts</li>
<ol>
<li>] lambda -&nbsp;a function (or a subroutine) defined, and possibly called, without being bound to an identifier; functions are first class citizens,&nbsp;</li>
<li>] dynamic objects - you can change or alter the properties of an object 'on the fly' (during program runtime) VS classical typed systems where objects are defined in class at design time +] prototypal inheiritance -&nbsp;</li>
<li>] object literals - the inspiration for the json data interchange format</li>
<li>] loose typeing -&nbsp;js has no type system, an advantage</li>
</ol>
<li>[<a href="http://www.youtube.com/watch?v=hQVTIJBZook&amp;feature=player_detailpage#t=1920" target="_blank">23:40</a>] prototypal inheiritance&nbsp;</li>
<ol>
<li>class free, you can do class style programming in&nbsp;</li>
<li>objects inheirit directly from other objects</li>
<li>object contains a link to another object, delegation, differential inheiritance</li>
<li>each object contains only what makes it different from the object that it inherits from, this allows it to be much smaller</li>
<li>Object.create statement came in ES5 to implement this much cleaner then the previous way of doing it</li>
<li>[24:55] example code - orig style of create</li>
<li>the new operator is requred when calling a constructor function</li>
<li>w/out the 'new' the compiler will clobber the global object with no ERRORS or WARNINGS, he doesnt use 'new'</li>
<li>?? new VS Object.create()</li>
</ol>
<li>[<a href="http://www.youtube.com/watch?v=hQVTIJBZook&amp;feature=player_detailpage#t=1580" target="_blank">26:20</a>] closure example</li>
<ol>
<li>] digit_name function in the global object, could easily be 'messed' up by another function using 'names'</li>
<li>] 1st approach is define the "names" array in as a private variable in the names function</li>
<li>] PRB is that every time the function is called, we will need to re-init the names array</li>
<li>] function that returns another function,&nbsp;</li>
<li>] var digitName = function(){</li>
<li>&nbsp; &nbsp; var names = ['one', 'two','three']</li>
<li>&nbsp; &nbsp; &nbsp;return function(n){</li>
<li>&nbsp; &nbsp; &nbsp; &nbsp; return names[n];&nbsp;</li>
<li>&nbsp; &nbsp; &nbsp;};</li>
<li>&nbsp;}();</li>
<li>alert(digitName(2)); //returns 3</li>
<li>we can generalize this into a constructor pattern</li>
<li>we dont have to make a class to make a singleton, we can just make it</li>
</ol>
<li>[<a href="http://www.youtube.com/watch?v=hQVTIJBZook&amp;feature=player_detailpage#t=1700" target="_blank">28:20</a>] module pattern is easily transformed into a powerful constructor pattern</li>
<ol>
<li>] make an object using 1 of 4 methods ] object literal ] new ] object create ] call another power constructor</li>
<li>] define variables and functions - these become private members</li>
<li>] augment the object with 'priviledged' methods which have unique access to the stuff defined in step 2</li>
<li>] return the object</li>
</ol>
<li>[<a href="http://www.youtube.com/watch?v=hQVTIJBZook&amp;feature=player_detailpage#t=1770" target="_blank">29:30</a>] template power constructor</li>
<ol>
<li>] function myPowerConstructor(){</li>
<li>&nbsp; &nbsp; &nbsp;var that = otherMaker(x);</li>
<li>&nbsp; &nbsp; &nbsp;var secret = f(x);&nbsp;</li>
<li>&nbsp; &nbsp; &nbsp; &nbsp; that.priv = function(){</li>
<li>&nbsp; &nbsp; &nbsp; &nbsp; // secret x that &nbsp;</li>
<li>&nbsp; &nbsp; &nbsp; &nbsp; };</li>
<li>&nbsp; &nbsp; &nbsp;return that;</li>
<li>&nbsp; &nbsp;}</li>
<li>*] easy way to make objects that can hide their members and be private</li>
<li>] reason we can do this is because we have closure</li>
<li>] function object CONTAINS function name, params body AND a reference to the environment in which it was created(context) (in the example the outer function)&nbsp;</li>
</ol>
<li>[<a href="http://www.youtube.com/watch?v=hQVTIJBZook&amp;feature=player_detailpage#t=1840" target="_blank">30:40</a>] style&nbsp;</li>
<li>] json</li>
<li>] jslint&nbsp;</li>
<li>] interesting&nbsp;</li>
<ol>
<li>] c syntax is terrible,&nbsp;</li>
<ol>
<li>? = why</li>
</ol>
<li>] html 5 - is going in the wrong direction,&nbsp;</li>
<ol>
<li>] would like to see a &nbsp;more 'minilimast' approach</li>
</ol>
<li>] idea to work around the global variable problem&nbsp;</li>
<ol>
<li>] modules</li>
</ol>
<li>]&nbsp;</li>
</ol>
<li>] REF</li>
<ol>
<li>] VIDEO http://www.youtube.com/watch?v=hQVTIJBZook&nbsp;</li>
<li>]&nbsp;&lt;iframe width="640" height="390" src="//www.youtube.com/embed/hQVTIJBZook" frameborder="0" allowfullscreen&gt;&lt;/iframe&gt;</li>
<li>] google tech talks 2009-02-21</li>
<li>] book <a href="https://play.google.com/books/reader?id=PXa2bby0oQ0C&amp;printsec=frontcover&amp;output=reader&amp;hl=en&amp;pg=GBS.ZZ0" target="_blank">js the good parts</a>&nbsp;- free sample on google play, book sells there for $14.65, 174 pages</li>
<li>] language-javascript&nbsp;</li>
</ol></ol>
<h2>[the book]</h2>
<div><ol>
<li>reviewers = x] Steve Souders, x] Stoyan Stefanov,</li>
<li>] Bill Scott(<a href="http://looksgoodworkswell.blogspot.ca/">http://looksgoodworkswell.blogspot.ca/</a>), wagbee&nbsp;</li>
<li>] Julien Lecomte, &nbsp;Eric Miraglia, and Elliotte Rusty Harold.</li>
<li>theory of strong typing - catch a large class of error at compile time</li>
<li>theory of loose typing - dont have to deal with the type system, liberating,&nbsp;</li>
<li>prototypal inheirtance - class free object system in which objects inheirit properties directly from other objects, poweful but unfamiliar to classic OOP programming, if you try to apply classical oop design patterns to js you will be frustrated, if you learn to work with js prototypal nature your efforts will be rewarded &nbsp;</li>
</ol></div>
</div>

~ view article ~ Chapter] ch-028-reference FROM [ Book] language-javascript IN [ libraries] technology-developer-www