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From: Dr J R Stockton <reply1142@merlyn.demon.co.uk>
Newsgroups: comp.lang.javascript
Subject: Re: Parsing String of Named Function & Converting To Source
Date: Wed, 19 Oct 2011 20:09:52 +0100
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In comp.lang.javascript message <8voi2r92.fsf@gmail.com>, Tue, 18 Oct
2011 18:34:17, Lasse Reichstein Nielsen <lrn.unread@gmail.com> posted:

>Seni Seven <OneWhoLovesYou@humanitarian.ca.invalid> writes:
>
>> Suppose I have HTML markup with a SCRIPT element as shown below:
>>
>>   <script type="text/javascript">
>>   function multiply(a, b) {
>>      return a * b;
>>   }
>>   var i = multiply(2, 5);
>>   document.write("The value of <i>i</i> is " + i);
>>   </script>
>>
>> All of this markup and contained script code is retrieved as a string using
>> Ajax.

>> I have an HTML parser with support for parsing the string containing the
>> script code.

>> In parsing the contained code (using JavaScript, of course), how would you
>> convert the contained script code from string into source?

>> ...

>> the value of identifier 'i' is immediately set to 10 in the debugger, but
>> the debugger exits with error 'multiply is not defined', which indicates
>> multiple levels of execution contexts, I suppose.  In fact, if I just do an
>> eval() on the "multiply" assignment of the Function constructor, the
>> identifier 'multiply' is still not defined.
>>
>> QUESTION:  What's the solution to the goal I want to achieve?


I've done that, or something rather similar, in
<http://www.merlyn.demon.co.uk/js-randm.htm> - the code for inserting
Johannes Baagoe's (or other) functions.  IIRC, it was necessary to be
slightly subtle about the argument to 'eval', perhaps such as something
like prepending " XXX = " to the function - see the source code of the
page.



>Try:
>  var script = document.createElement("script");
>  script.textContent = sourceString;
>  document.body.appendChild(script);
>This executes the code as top-level, non-eval code (which there is no way
>to do in pure Javascript).
>No guarantees wrt. old browsers, but it seems to work in the current versions.
>
>Alternatively, just use a non-direct call to eval.
> var topLevelEval = eval;
> topLevelEval(sourceString);

Would any of your contribution give a worthwhile improvement in the
cited js-randm.htm, given that the latter works?

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