assign values to numeric indexed multidimensional array jquery

Question

i want to loop a jquery selector using .each() and assign values to a multidimensional array $record. here is what i tried and it doesnt work

JQUERY:

var $record = new Array(),
    i=0,
    x,y;
$("td").each(function(){       
    x = Math.floor((i+1)/4),
    y = i%4;
    $record[x][y] = true;    
    i++;
});

CHROME CONSOLE ERROR: Uncaught TypeError: Cannot set property '0' of undefined

That is one strange looking array, can't imagine how you'd access that and figure out the keys ? — adeneo
– adeneo, Commented Apr 26, 2014 at 16:51

Rajaprabhu Aravindasamy · Accepted Answer · 2014-04-26 16:50:13Z

1

That error is raising because you did not define the inner array.

Try,

$("td").each(function(){       
    x = Math.floor((i+1)/4),
    y = i%4;
    if(!$.isArray($record[x])) { $record[x] = []; }
    $record[x][y] = true;    
    i++;
});

answered Apr 26, 2014 at 16:50

Rajaprabhu Aravindasamy

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Comments

Johan · Accepted Answer · 2014-04-26 17:00:31Z

0

Consider this

var record = [],
    i = 0,
    x = Math.floor((i+1)/4),
    y = Math.floor((i+1)/4)

console.log(record); // 0
console.log(record[0]); // undefined
console.log(record[x][y]); // Uncaught TypeError: 
                           // Cannot read property '0' of undefined

First iteration, i is 0. You're trying to access an element that doesn't exist. Or to be even more specific, the property 0 on the array, which would exist if there was an element on index 0.

In other words, if you add something to the array, it would get it's property:

record[0] = 'something';
console.log(record['0'], record.hasOwnProperty('0')); // 'something', true

answered Apr 26, 2014 at 17:00

Johan

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