| Re: How to convert this PHP into JavaScript [message #173179 is a reply to message #173176] |
Sat, 26 March 2011 09:28   |
Thomas 'PointedEars'
Messages: 701
Registered: October 2010
Karma:
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Senior Member |
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Curtis Dyer wrote:
> sheldonlg wrote:
>
> This is one of those cases in which I feel that cross-posting is
> viable. The problem here is that the OP needs advice on how to
> generate *quality* target code from PHP. Therefore, quality
> JavaScript advice form people who are aware of subtle issues like
> automatic semi-colon insertion (ASI), ECMAScript string literal
> syntax, etc. are necessary.
Generally, full ACK. But I think it is no longer necessary in this case.
>> I just, two days ago, had a need to do just that. What I did
>> was:
>
> I would consider outputting the below outside of PHP tags
Exactly.
> or perhaps using heredoc syntax.
I have found heredoc syntax to be tedious with indentation, and editors
incapable of proper syntax highlighting of non-PHP code in heredoc strings,
so I have begun to avoid it.
>> print "<script>\n";
>> print " var foo = new Array();\n";
>
> Less verbose would be:
>
> var foo = [];
>
>> print " foo[0] = " . $foo[0] . ";\n";
>
> You give no evidence here that `$foo[0]' is properly escaped to be
> included in a string literal
It is inefficiently written, too. Consecutive `echo' or `print' statements
are almost always a sign of cluelessness; in this case, the statements
should have been replaced at first by
?><script>
var foo = [
<?php echo $foo[0]; ?>,
/* etc. (generating the array for javascript) */
];
function myFunc(i)
{
/* do stuff with the foo[i] */
}
</script><?php
Note that the Array literal should not have a trailing comma, for ECMAScript
implementations differ there. The global variable should be avoided in the
first place, of course. And there is still no "javascript":
> There are important differences between PHP's and JavaScript's one needs
> to keep in mind.
One being that JavaScript is only one of many implementations of ECMAScript,
a standard for an extensible programming language.
> In addition to properly escaping quotes and backslashes,
> one needs to take care that the JavaScript string literal has no actual
> line terminators hard coded into it:
Unless preceded by backslash, which has been standardized by ECMAScript
Edition 5, but AFAIK cannot be considered safe to date (thanks to Opera).
> If I haven't missed anything, one way to escape the output for
> JavaScript in PHP might look like:
>
> $escaped = addcslashes($foo[0], "\"\n\r\\'");
You have missed json_encode(), which does that *and* safe encoding of other
Unicode characters, independent of the character encoding of the resulting
document.
PointedEars
--
realism: HTML 4.01 Strict
evangelism: XHTML 1.0 Strict
madness: XHTML 1.1 as application/xhtml+xml
-- Bjoern Hoehrmann
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