FireFox, Safari, and Opera ... JavaScript Conditional Comment

I've still written a comment in John Resig blog about Re-Securing JSON and FireFox or Safari 3 const behaviour to create an immutable function, called Native, and to retrieve original Array, Object, String or other constructors.

This is the function:

const Native = (function(){
 const NArray = Array,
  NBoolean = Boolean,
  NDate = Date,
  NError = Error,
  NMath = Math,
  NNumber = Number,
  NObject = Object,
  NRegExp = RegExp,
  NString = String;
 return function(Native){
  switch(Native){
   case Array:return NArray;
   case Boolean:return NBoolean;
   case Date:return NDate;
   case Error:return NError;
   case Math:return NMath;
   case Number:return NNumber;
   case Object:return NObject;
   case RegExp:return NRegExp;
   case String:return NString;
  };
 };
})();

// Example
Array = Native(Array);
eval("[1,2,3]");

At the same time I've talked about IE behaviour and its missed support for const.

While I was thinking about that I imagined a way to use a piece of code, in this case the keyword const, compatible with every browser.

It should sounds simple, just use the well know trick IE=/*@cc_on ! @*/false; followed by if(IE) ... but ... hey, I need everytime to create a double version of the "same script" ... is it good?

Try to imagine a variable that should be a constant for every compatible browser but at the same time should be declared just one time ...

const MyConstant = 1;

With every day practices we should use a try catch or some strange trick to evaluate a const declaration ... don't we?

But we have a particular behaviour of the conditional comment ... it should contains a comment itself too, sounds cool?

/*@cc_on // @*/ const
Native = function(){
 // whatever You need
};

Can anyone trigger an error with above piece of code? :-)

In this way FireFox 2+, Safari 3+ (I don't know about 2), and Opera 9+ could work without problems disabling Native variable re-declaration while every IE browser will ignore the const keyword.

I suppose this trick is not so new but never as this time it should be useful to make code more slim and efficient.

Instant Update
The usage of const inside the private scope of Native function declaration is not so useful (just a little bit of paranoia :D) but in these cases we could use a better trick to create local variables with internet explorer too.

This is an example:

Native = (function(){
 /*@cc_on var // @*/ const
 NArray = Array,
 NBoolean = Boolean;
 return function(Native){
  return Native === Array ? Narray : NBoolean;
 };
})();

Above example shows how should be possible to initializzate multiple variables using a comma and respecting the private scope.
Internet Explorer will use var while every other browser will try to use const if it's compatible.

Sounds even better? I hope so :-)

P.S. Native function is quite interesting, imho, that's why I choosed to add them in devpro.it

Looking for a job in London ... or not?

It's about 2 weeks that I'm studying in London to improve my English knowledge, specially my spoken one (I know, written is not so perfect too).

I put my cv on line in a famous recluting search engine but it seems that most interested people are Agency's employees that usually look for generic IT - Web masters.

I would like to explain my "strange situation": I am not absolutely a web designer, I do know quite nothing about graphic, I could just know how to start Gimp!!! :D

It seems that if You know quite perfectly ActionScript 1.0/2.0, that's basically ECMAScript 3rd edition or, in case of 2.0, 4th one closed, you can be only a Web Designer and not a programmer, even if You know Flash Player bugs and you're able to find out workarounds.

It seems that if You know deeply JavaScript (best practices, OOP, Ajax, cross-browser/platform development, bugs, common libraries suggestions) it's not important ... just a preferred plus ... but at the same time everybody is looking for Ajax and Web 2.0 skilled developers, a role that absolutely requires a good programming background (not just a bit of DreamWeaver).

It seems that if you know different languages or technologies ... there's always a missed one.
How can a person to be "senior in every program language"?
I can't call their "expert or senior everything developers", a part for someone who has at least 20 years or more experience.

However, excellent OO PHP 4/5,JavaScript,ActionScript,(x)HTML,CSS,XML skills aren't enough while a good knowledge of C# for ASP.NET or MONO, and Python is not enough as a technical plus.

Maybe someone should be interested in my good database skills, starting from SQLite 2/3 to MySQL 3/4/5, passing inside PostgresSQL ... but it's not enough.

What about security practices and code optimization skills? Who cares about that!

As sum, and as someone said before me: please hire me !!! :-)

Best regards,
Andrea Giammarchi

A quite totally standard enviroment before ECMAScript 4th Edition in less than 3Kb - JSL 1.8+

JavaScript Standard Library Revision

After the success of my old JSL project I learned more about JavaScript and I found some trick to solve different problems such setInterval and extra arguments for Internt Explorer, a function to evaluate code in a global scope with every browser as Internet Explorer does with its proprietary execScript.

Since these days We're waiting for ECMAScript 4th Edition, aka JavaScript 2 but since We always don't know when it should be really usable within productions, I choosed to create a revisited version of JavaScript Standard Library.

I removed Internet Explorer 4 support but I modified a lot of common prototyes to make them faster, more standard and more scalable than ever.
You can use, for example, every JS 1.6+ Array.prototype with HTMLCollections too as it's possible from many Years with FireFox or Safari:

Array.prototype.forEach.call(document.getElementsByTagName("div"), function(node){
        alert(node.innerHTML);
});

I fixed different standard behaviours and I implemented setTimeout and setInterval.
I add execScript, not standard, but really useful when You need to evaluate JavaScript in a global scope with FireFox, Safari, Opera and every other as Internet Explorer does from many years with its own execScript global function.


JSL creates a quite totally standard JavaScript 1.6+ enviroment adding prototypes only to browsers that don't support them or that have different behaviours and everything in a hilarious size of 2.53 ... 2.86 Kbytes (gzipped) - new size is caused by an instant update, an XMLHttpRequest constructor (a wrapper) to allow every IE 5 to 7 browser to define XMLHttpRequest prototypes too.

With JSL You can forget your own not always standard prototypes implementations so every library size could decrease its code quickly, basing them on standard JavaScript 1.6+ enviroment and increasing performances for every standard browser like FireFox or Safari (about 40% of users ... growing up every day!).

This is the last chance to have a more standard Internet Explorer implementation because if We need to wait their fixes We should go better to sleep.

Have fun with JSL Revision and a quite real ECMAScript 3rd Edition enviroment.