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Message-ID: <1931071.aqSPkdTlGX@PointedEars.de>
From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Reply-To: Thomas 'PointedEars' Lahn <cljs@PointedEars.de>
Organization: PointedEars Software (PES)
Date: Tue, 27 Dec 2011 18:27:03 +0100
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Subject: Re: Simulate goto
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Tom de Neef wrote:

> "Archos" <raul.san@sent.com> schreef […]
>> I'm trying to simulate the goto statement but I get an error
>>
>> ===
>> function testGoto() {
>> var isFirst = true;
>>
>> skipPoint:
>> alert("Using goto\n");
>>
>> if (isFirst) {
>> isFirst = false;
>> continue skipPoint;
>> alert("This part is skipped");
>> }
>> }
>> ===
>>
>> SyntaxError: label not found
>> continue skipPoint;
> 
> The error may have more to do with 'continue' than with the label.
> Check where you can use a continue statement - I think it is restricted to
> for- and while- loops.

You are mistaken.  The `continue' statement, like the Labelled Statement is 
just another /Statement/, and it can be located anywhere in a /Program/:

,-[ES 5.1]
| 
| 14 Program
| 
| Syntax
| 
| Program :
|   SourceElements_opt
| 
| SourceElements :
|   SourceElement
|   SourceElements SourceElement
| 
| SourceElement :
|   Statement
|   FunctionDeclaration

,-[ibid.]
| 
| 12 Statements
| 
| Syntax
| 
| Statement :
|   Block
|   VariableStatement
|   EmptyStatement
|   ExpressionStatement
|   IfStatement
|   IterationStatement
|   ContinueStatement
|   […]
|   LabelledStatement
|   […]
| 
| 12.3 Empty Statement
| 
| Syntax
|   EmptyStatement :
|     ;
| 
| […]
| 12.7 The continue Statement
| 
| Syntax
| 
| ContinueStatement :
|   continue ;
|   continue [no LineTerminator here] Identifier;
| 
| […]
| 12.12 Labelled Statements
| 
| Syntax
| 
| LabelledStatement :
|   Identifier : Statement

`skipPoint' is an /Identifier/ and – through Automatic Semicolon Insertion 
(ASI) – an /EmptyStatement/ is a /Statement/.  One could try placing the 
/ExpressionStatement/ – alert(…) – at the same line as the label, but that 
should not be necessary in a conforming implementation (which implementation 
has been tested with?).

That said, it is certainly not a good idea to "simulate the goto statement".

Please do not post attribution novels: <http://insideoe.com/>


PointedEars
-- 
> If you get a bunch of authors […] that state the same "best practices"
> in any programming language, then you can bet who is wrong or right...
Not with javascript. Nonsense propagates like wildfire in this field.
  -- Richard Cornford, comp.lang.javascript, 2011-11-14