Javascript global array object can't be read

Question

I'm having a few issues and I think it is because of the way I'm declaring an array. I'm using jQuery and I want to declare a global array so I can use its items inside my functions. The way I'm doing it now, when I do try to use the items in a function, they are limited. I did a console log of the array and it seems to show that it has stuff in it (even the stuff that I want) but then when I perform jQuery functions on those items it tells me

Cannot read property 'top' of undefined

Additionally, I've not used arrays much in JS, just in C++, so perhaps there's an issue with my syntax? Here is a rough copy of the code I have:

var pigs = new Array();
pigs[0] = $('#foo');
pigs[1] = $('#bar');

$(document).ready(function(){
    console.log(pigs);
    var topCoord = pigs[0].offset().top;
});

first of all, do you have '<div id="foo"></div>' and '<div id="bar"></div>' — ElSinus
– ElSinus, Commented Nov 13, 2013 at 14:43
and write pigs[0] = $('#foo'); pigs[1] = $('#bar'); inside document ready — ElSinus
– ElSinus, Commented Nov 13, 2013 at 14:44
I hope you enjoy JS?! The more beautiful way to do Arrays is for example: var pigs = []; -- then in document.ready just do pigs.push( $('#foo') ) to fill it :) — riyuk
– riyuk, Commented Nov 13, 2013 at 14:46

score 2 · Accepted Answer · 2013-11-13 14:47:51Z

2

I guess $('#foo') and $('#bar') both return empty jQuery objects. You should wait for the DOM to be ready before querying it :

var pigs = new Array();
$(document).ready(function(){
    pigs[0] = $('#foo');
    pigs[1] = $('#bar');
    console.log(pigs);
    var topCoord = pigs[0].offset().top;
});

edited Nov 13, 2013 at 14:47

answered Nov 13, 2013 at 14:42

user1636522

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4 Comments

mavsman Over a year ago

If I assign those values in that function, will I still be able to use those objects and values in other functions? In other words, if I change it within that function, it will be changed globally as well right?

riyuk Over a year ago

Yes sir. Welcome to Javascript ;-)

user1636522 Over a year ago

@mavsman Sure, because the array is defined inside the global scope.

mavsman Over a year ago

Haha sadly, I've been using it for 6 months and never used arrays, yikes. Thanks for the help, it worked like a charm

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