Javascript Objects in Arrays

Question 1

I'm trying to use the Ajax File Upload as featured here: http://valums.com/ajax-upload/

As you can see, I need to create a qq.FileUploader object to initialize the script. However, I need to be able to dynamically create this objects without knowing the IDs of the elements. I've tried creating something like this:

var uploader, i = 0;
$(".file-upload").each(function() {
 $e = $(this);
 i++;
 uploader[i] = new qq.FileUploader({
 element: $(this)[0],
 action: 'uploadfile.php',
 allowedExtensions: ['doc', 'docx', 'pdf'],
 multiple: false,
 onComplete: function(id, fileName, responseJSON) {
 $($e).siblings('input').val(responseJSON.newfilename);
 }
 });
});

I've learned that the [i] part I have added breaks the script, because I cannot have objects inside of an array.

Is there another way I can create this objects dynamically? They need to all have a unique name, otherwise the onComplete function gets overwritten for all of them. I experimented with using eval(), but I can't seem to make it work correctly.

Question 2

$e = $(this); so you don't need to re-wrap it later. $e.siblings('input').val(responseJSON.newfilename); also $(this)[0] is redundant. just use element: this, also you can remove i++; and just put uploader[++i] = new qq.FileUploader({... scratch that.. you can change $(".file-upload").each(function() { to $(".file-upload").each(function(i) { and leave out the variable i and increment all together. tl;rd

Question 3

here is a demo with uploader.push() for kicks

Question 4

You have to declare uploader as an array first :

var uploader = [];

Because you declared the variable without defining it, it has the default value of undefined , and your code was translated into something like undefined[i] which triggers an error.

Question 5

i feel like assigning something to the array in this fashion is a strange idea, would rather use uploader.push()

Question 6

developer.mozilla.org/en-US/docs/JavaScript/Reference/… like you would with an Array??? :P

Question 7

what exactly do you mean, @rlemon?

Question 8

You are advocating using Array.push; yet your answer assigns the variable as a object.

Question 9

@rlemon because both options are valid. Either [] and uploader.push(), or {} and uploader.[i] = ....

Question 10

Has to be something like

var uploader = {};

or else uploader is null and you cannot assign anything to it.

EDIT:

So there're two opitions, in my opinion, if one wants to have an array than it makes sense to declare one, var uploader = []; and then use the uploader.push() method or define it as an object var uploader = {}; and just do uploader[i] = ....

It is also possible to do the latter with an a array, but in the latter case I see no point in maintaining the counter (i).

Question 11

I didn't downvote, because this answer is not really wrong, but it's more likely that the OP wants a real array and not just an object as the indexes are numeric. Thus, var uploader = []; is probably a better answer.

Question 12

@Pointy I agree, but then array.push() sounds more appropriate to me, as I already pointed out above.

Question 13

TypeError: Object #<Object> has no method 'push'

Question 14

@rlemon, that's my point exactly, if you declare something to be an array, than it makes sense to use array-specific functions such as push(). If you want to just do something[i] = 'whatever', than it's fine to just have an object.

Question 15

@Qnan well except that an array will automatically maintain the .length property regardless of how properties (with numeric "names") are added.

gion_13 41.5k10 gold badges99 silver badges111 bronze badges · Accepted Answer · 2012-08-19 17:44:04Z

2

You have to declare uploader as an array first :

var uploader = [];

Because you declared the variable without defining it, it has the default value of undefined , and your code was translated into something like undefined[i] which triggers an error.

Share

Improve this answer

answered Aug 19, 2012 at 17:44

gion_13's user avatar

gion_13

41.5k10 gold badges99 silver badges111 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Qnan

Qnan Over a year ago

i feel like assigning something to the array in this fashion is a strange idea, would rather use uploader.push()

2012年08月19日T17:47:29.34Z+00:00

rlemon

rlemon Over a year ago

developer.mozilla.org/en-US/docs/JavaScript/Reference/… like you would with an Array??? :P

2012年08月19日T17:50:00.48Z+00:00

Qnan

Qnan Over a year ago

what exactly do you mean, @rlemon?

2012年08月19日T17:50:48.513Z+00:00

rlemon

rlemon Over a year ago

You are advocating using Array.push; yet your answer assigns the variable as a object.

2012年08月19日T17:51:55.133Z+00:00

Qnan

Qnan Over a year ago

@rlemon because both options are valid. Either [] and uploader.push(), or {} and uploader.[i] = ....

2012年08月19日T17:54:18.89Z+00:00

|

CollectivesTM on Stack Overflow

Javascript Objects in Arrays

2 Answers 2

7 Comments

7 Comments

Your Answer

Sign up or log in

Post as a guest

Post as a guest

Hot Network Questions

CollectivesTM on Stack Overflow

2 Answers 2

7 Comments

7 Comments

Your Answer

Sign up or log in

Post as a guest

Post as a guest

Related