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JavaScript for loop ends prematurely when using String.length, why?

  • 6 respostas
  • 2 têm este problema
  • 36 visualizações
  • Última resposta de awasen

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Ok, I have this JavaScript code:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

//current.value contains, e.g. /tmp/myFile.txt

var filename = "";

var tmp = "";

for (var j = 0; j < current.value.length; j++) {

tmp = current.value.substr(current.value.length-j,1);

if (tmp.length > 0) {

if ((tmp.charCodeAt(0) == 92) || (tmp.charCodeAt(0) == 47)) break;

filename = tmp + filename;

}

}

alert(filename);

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I want to get the file name out as "myFile.txt". This works fine in IE8 & 9, Chrome and Opera, but not in FireFox 4. In FF4 I always get "yFile.txt" as the loop ends one position sooner than all the other browsers.

(And, yes, I know this can be done using reg.exp. but due to a PHP bug I can not use the reg.exp. expression using \\ (double back-slashes) so I had to come up with a work-around).

Regards, Anders

Ok, I have this JavaScript code: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ //current.value contains, e.g. /tmp/myFile.txt var filename = ""; var tmp = ""; for (var j = 0; j < current.value.length; j++) { tmp = current.value.substr(current.value.length-j,1); if (tmp.length > 0) { if ((tmp.charCodeAt(0) == 92) || (tmp.charCodeAt(0) == 47)) break; filename = tmp + filename; } } alert(filename); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I want to get the file name out as "myFile.txt". This works fine in IE8 & 9, Chrome and Opera, but not in FireFox 4. In FF4 I always get "yFile.txt" as the loop ends one position sooner than all the other browsers. (And, yes, I know this can be done using reg.exp. but due to a PHP bug I can not use the reg.exp. expression using \\ (double back-slashes) so I had to come up with a work-around). Regards, Anders

Alterado por cor-el em

Todas as respostas (6)

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Try posting at the Web Development / Standards Evangelism forum at MozillaZine. The helpers over there are more knowledgeable about web page development issues with Firefox.
http://forums.mozillazine.org/viewforum.php?f=25
You'll need to register and login to be able to post in that forum.

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Thanks for taking time to respond!

I have created a thread there instead. Anyone who wants to follow it can find it here: http://forums.mozillazine.org/viewtopic.php?f=38&t=2207267&e=0

Regards, Anders

Alterado por awasen em

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Maybe it is better to start with j=1 because strings start at 0 until length-1 and substr(current.value.length-0) is not defined.

  • current.value.substr(current.value.length-j,1);
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Thanks cor-el, you are correct, but unfortunately the issue is that the loop exits one "revolution" too soon. Like in my sample it bails out one character too soon so "abcd" becomes "bcd"...

Regards, Anders

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for (var j = 1; j <= current.value.length; j++)

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)

Well, the problem is with this line: if ((tmp.charCodeAt(0) == 92) || (tmp.charCodeAt(0) == 47)) break;

If it finds a front- or back-slash it should bail out from the for-loop. The problem is that it bails out one character too soon...

Regards, Anders