Creating arrays and datasets with javascript and jquery

Question

I write a code that will arrange me a points sinside table, but when I specific arrayOfDivs all works great: http://jsfiddle.net/u58k6/6

var arrayOfDivs = [({topPosition : 99, leftPosition: 100}),({topPosition : 150, leftPosition: 400}),({topPosition : 578, leftPosition: 10})];

When I try to dinamicly creating this arrayOfDivs based on other things, when I add this code to create arrayOfDivs:

var arrayOfDivs = [];

$("#table .draggable").each(function(index, item){
   var lat = $(item).attr("lat");
   var lng = $(item).attr("lng");
   var top = $(this).position().top;
   var left = $(this).position().left;
   arrayOfDivs.push({topPosition : top, leftPosition: left, lat : lat, lng : lng});
});

var height = $('table').height();
var rowsCount = $('table tr').length;
var ROW_HEIGHT = height/rowsCount;

FINAL VERSION: http://jsfiddle.net/u58k6/10/ , I just get this error in console: Uncaught TypeError: Cannot call method 'push' of undefined

Why? What is the prob;em?

nnnnnn · Accepted Answer · 2013-07-28 10:53:27Z

1

Your arrayOfDivs is being created successfully.

The TypeError is occurring on a line not shown in your question. It's here:

var rowNumber = Math.floor(position.topPosition / ROW_HEIGHT);
rows[rowNumber].push(position);

Because position.topPosition can be negative that means rowNumber can be negative, which means that you're trying to do rows[-1].push(position) which is essentially undefined.push(position).

(Add a console.log(rowNumber); statement just before the .push() and you'll see the -1.)

You don't have this problem when you hard-code the arrayOfDivs because none of the positions that you've specified are negative. It's when you get the positions of actual elements on the page that you might get negative numbers.

I don't have a specific suggestion for how to fix this, because I'm not (yet) sure what you're actually trying to achieve. But I hope that's enough for you to go on to fix it yourself.

edited Jul 28, 2013 at 10:53

answered Jul 28, 2013 at 10:47

nnnnnn

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4 Comments

Mark West Over a year ago

I try but again is the same Uncaught TypeError: Cannot call method 'push' of undefined

Mark West Over a year ago

what I try to do is: arragnge divs in arrays , first by rows, so one row = one new array, after that arrange by left every new array created

Mark West Over a year ago

please try to fix that

nnnnnn Over a year ago

Well you could add if(rowNumber<0){ rowNumber = 0; } just after the var statement I quoted.

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