up vote8down votefavorite

1) I have this Javascript array:

lang=new Array();
lang["sq"]="Albanian";
lang["ar"]="Arabic";
lang["en"]="English";
lang["ro"]="Romanian";
lang["ru"]="Russian";

2) In some other process, there is a returned value in a variable:

result.detectedSourceLanguage = 'en';

3) Now, i want to print the language full name by doing this:

alert(lang[result.detectedSourceLanguage]);

The dialog displays: undefined

Any ideas?

BTW: im using JQuery, so JQuery solutions are welcomed.

 
shareimprove this question
  • Did you try using index's? 0,1,2,3? When declaring variable did you use VAR? Try also calling that variable "resultDetectedSourceLanguage"... Dont know what else to say... :) – Gavrisimo Sep 6 '09 at 2:47
  • May be check that you have the array defined by the time you are trying to access it. BTW What do you mean by "in some other process"? – Jaime Sep 6 '09 at 2:49
  • if i call: alert(lang['en']); it prints English as it should. The problem is when i do this: alert(lang[var1]); (where var1 holds 'en' value). – Andres SK Sep 6 '09 at 2:55
  • Well that assertion is impossible; regardless of your misuse of Array (should be Object, {}), JavaScript does allow this, and your code above does work as expected. There is something else happening; post a full test case that fails. – bobince Sep 6 '09 at 23:40

4 Answers 正确答案 

up vote21down voteaccepted

An Array uses integer indexes. You probably want an Object, which supports string indexes:

lang=new Object();
lang["sq"]="Albanian";
lang["ar"]="Arabic";
lang["en"]="English";
lang["ro"]="Romanian";
lang["ru"]="Russian";

// or

lang = {
    'sq': 'Albanian',
    'ar': 'Arabic',
    // ...
    'ru': 'Russian'
};

(The latter example is probably better as more JS programmers would be happy with it.)

shareimprove this answer
  • 1
    Just a note on why the OP sometimes worked: In JS Arrays are objects, so you can attach arbitrary properties to them as you can with any other object. As was found though, these additional properties can get lost if the array is serialized to its normal ['val 1', 'val 2', 'val 3, ...] syntax. Its likely that somewhere in JQuery or elsewhere a serialization/deserialization is happening to the array, and the additional properties are lost. – Adam Franco Sep 6 '09 at 4:36
  • I know an Array is an Object, but really, you should treat it as a sequential array (like std::vector in C++'s STL) and not an associative array (like std::map in C++'s STL or PHP-like arrays), to avoid confusion. Serialization/conversion may be the problem as you suggest, Adam. – stragerSep 6 '09 at 5:16
up vote3down vote

This script generates a message box (checked in IE & FF) that says "English":

lang = new Array();
lang["sq"] = "Albanian";
lang["ar"] = "Arabic";
lang["en"] = "English";
lang["ro"] = "Romanian";
lang["ru"] = "Russian";

detectedSourceLanguage = 'en';

alert(lang[detectedSourceLanguage]);

The only problem could be the result object.

shareimprove this answer
up vote1down vote

Check the type and value of result (and result.detectedSourceLanguage). It could be one of the following

  • result is not defined

  • result is not an object or doesn't have any attribute named detectedSourceLanguage

  • Value of result.detectedSourceLanguage is not a string or there's no such key in lang (then it's supposed to return undefined for alert(lang[result.detectedSourceLanguage]); )

BTW, your problem has nothing to do with jQuery

shareimprove this answer
  • that has nothing to do with the prob. if i call: alert(lang['en']); it prints English as it should. – Andres SK Sep 6 '09 at 2:54
up vote0down vote

Try alerting result.detectedSourceLanguage immediately prior to its use. There is a chance that it doesn't equal what you expect it to. This should work.

shareimprove this answer

来自  https://stackoverflow.com/questions/1384746/finding-string-key-in-javascript-array