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GarethAtFlignet

2008-Jan-16 10:13 UTC

Prototype and JavaScript eval statement

HI there,

I''m trying to improve the performance of an application we''re
working
on which makes a fair bit of use of the eval statement. We''re tryignt
o weed out the use of eval due to the performacne overhead and there
is one section of code we haven''t as yet been able to improve upon.
Any help very much appreciated.

Here is a sample code snipped. The key points which ''cannot''
be
changed is that the classname must be sourced from a variable and not
static (same for the parameters).

		var widgetName = "Button";
		var widgetParam1 = "I am parameter 1";
		var widgetParam2 = new Array("I am ", "parameter 2");
		eval("var myWidget = new "+widgetName+"(widgetParam1,
widgetParam2);");

Many thanks
Gareth
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Bertilo Wennergren

2008-Jan-16 10:24 UTC

head link

Re: Prototype and JavaScript eval statement

GarethAtFlignet wrote:
> Here is a sample code snipped. The key points which
''cannot'' be
> changed is that the classname must be sourced from a variable and not
> static (same for the parameters).
> 
> 		var widgetName = "Button";
> 		var widgetParam1 = "I am parameter 1";
> 		var widgetParam2 = new Array("I am ", "parameter 2");
> 		eval("var myWidget = new "+widgetName+"(widgetParam1,
> widgetParam2);");
I suppose you could do something like this:

   var widget1 = new Object(); // Wherever the widgets come from...
   var widget2 = new Object();
   [...]
   var Widgets = new Object();
   Widgets[someWidgetname] = widget1;
   Widgets[anotherWidgetname] = widget2;
   [...]

   var widgetName = "Button";
   var widgetParam1 = "I am parameter 1";
   var widgetParam2 = new Array("I am ", "parameter 2");
   var myWidget = new Widgets[widgetName](widgetParam1, widgetParam2);

(I''ve never tried anything like that, but I suppose it must
be possible...)

-- 
Bertilo Wennergren <http://bertilow.com>

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Richard Quadling

2008-Jan-16 10:27 UTC

head link

Re: Prototype and JavaScript eval statement

Could you use ...

var myWidget = document.createElement(widgetName);

and then set the properties as normal?

On 16/01/2008, GarethAtFlignet
<garethinwales-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
wrote:>
> HI there,
>
> I''m trying to improve the performance of an application
we''re working
> on which makes a fair bit of use of the eval statement. We''re
tryignt
> o weed out the use of eval due to the performacne overhead and there
> is one section of code we haven''t as yet been able to improve
upon.
> Any help very much appreciated.
>
> Here is a sample code snipped. The key points which
''cannot'' be
> changed is that the classname must be sourced from a variable and not
> static (same for the parameters).
>
>                 var widgetName = "Button";
>                 var widgetParam1 = "I am parameter 1";
>                 var widgetParam2 = new Array("I am ",
"parameter 2");
>                 eval("var myWidget = new
"+widgetName+"(widgetParam1,
> widgetParam2);");
>
> Many thanks
> Gareth
> >
>

-- 
-----
Richard Quadling
Zend Certified Engineer : http://zend.com/zce.php?c=ZEND002498&r=213474731
"Standing on the shoulders of some very clever giants!"

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GarethAtFlignet

2008-Jan-16 10:37 UTC

head link

Re: Prototype and JavaScript eval statement

Sorry Richard I should have put in the Button object for you to look
at as well, its not a html element but a prototype class:

		<script>
		var AbstractWidget = Class.create({
			widgetParam1: null,
			widgetParam2: null,
			initialize: function(widgetParam1, widgetParam2) {
				this.widgetParam1 = widgetParam1;
				this.widgetParam2 = widgetParam2;
			},
		});
		var AbstractComponent = Class.create(AbstractWidget, { } );
		var Button = Class.create(AbstractComponent, { } );
		</script>


On Jan 16, 10:27 am, "Richard Quadling"
<rquadl...-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
wrote:> Could you use ...
>
> var myWidget = document.createElement(widgetName);
>
> and then set the properties as normal?
>
> On 16/01/2008, GarethAtFlignet
<garethinwa...-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org> wrote:
>
>
>
>
>
> > HI there,
>
> > I''m trying to improve the performance of an application
we''re working
> > on which makes a fair bit of use of the eval statement. We''re
tryignt
> > o weed out the use of eval due to the performacne overhead and there
> > is one section of code we haven''t as yet been able to improve
upon.
> > Any help very much appreciated.
>
> > Here is a sample code snipped. The key points which
''cannot'' be
> > changed is that the classname must be sourced from a variable and not
> > static (same for the parameters).
>
> >                 var widgetName = "Button";
> >                 var widgetParam1 = "I am parameter 1";
> >                 var widgetParam2 = new Array("I am ",
"parameter 2");
> >                 eval("var myWidget = new
"+widgetName+"(widgetParam1,
> > widgetParam2);");
>
> > Many thanks
> > Gareth
>
> --
> -----
> Richard Quadling
> Zend Certified Engineer
:http://zend.com/zce.php?c=ZEND002498&r=213474731
> "Standing on the shoulders of some very clever giants!"--~--~---------~--~----~------------~-------~--~----~
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Tobie Langel

2008-Jan-16 10:50 UTC

head link

Re: Prototype and JavaScript eval statement

Try:

var myWidget = new window[widgetName](widgetParam1, widgetParam2);

best,

Tobie
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GarethAtFlignet

2008-Jan-16 10:57 UTC

head link

Re: Prototype and JavaScript eval statement

Many Thanks all.

Tobie, didn''t think of using window (although silly me I do actually
test for window.widgetName beorehand to check if the class exists),
many many thanks.

Cheers
Gareth

On Jan 16, 10:50 am, Tobie Langel
<tobie.lan...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Try:
>
> var myWidget = new window[widgetName](widgetParam1, widgetParam2);
>
> best,
>
> Tobie--~--~---------~--~----~------------~-------~--~----~
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Richard Quadling

2008-Jan-16 11:18 UTC

head link

Re: Prototype and JavaScript eval statement

On 16/01/2008, Tobie Langel
<tobie.langel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:>
> Try:
>
> var myWidget = new window[widgetName](widgetParam1, widgetParam2);
>
> best,
>
> Tobie
Oh. Nice. Using the namespace of window to find an entity named by a
variable. Nice and abstract.

As I always say, we are all standing on the shoulders of some very
clever giants.


-- 
-----
Richard Quadling
Zend Certified Engineer : http://zend.com/zce.php?c=ZEND002498&r=213474731
"Standing on the shoulders of some very clever giants!"

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Rails spinoffs - Jan 2008 - Prototype and JavaScript eval statement

Prototype and JavaScript eval statement

Re: Prototype and JavaScript eval statement

Re: Prototype and JavaScript eval statement

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Re: Prototype and JavaScript eval statement

Re: Prototype and JavaScript eval statement