Array is undefined in For loop

Question

I get the following error (which doesn't make any sense to me !!):

TypeError: jImages[i] is undefined

Code:

$.ajax({ url: 'FilterByToestanden.php',
         data: {aantal: $("#aantToestanden option:selected").text(), tekst: $('#bevat').val()},
         type: 'post',
         success: function(data) {
                      var jImages = JSON.parse(data);
                      alert(jImages[0][0]);
                      var filteredImageList = new Array();
                      for (var i=0, len = data.length; i< len; i++)
                      {
                      filteredImageList[i]=jImages[i][0]+jImages[i][1];
                      }
                      alert(filteredImageList);
                  }
});

Barmar · Accepted Answer · 2013-10-29 14:10:09Z

4

data.length should be jImages.length.

data.length is the length of the JSON string, which is much more than the length of the jImages array. So you were going beyond the end of the array, resulting in trying to access undefined elements.

answered Oct 29, 2013 at 14:10

Barmar

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2 Comments

Faarbhurtz Over a year ago

Not sure why it wouldn't work otherwise, but it works now ! thanks

Barmar Over a year ago

You must be totally clueless if you don't understand the difference, but I added some explanation.

ProGM · Accepted Answer · 2013-10-29 14:13:52Z

2

data is a string (JSON string), and jImages is a 2d array. In general data.length (string character number) is different from jImages (number of elements inside the array).

you should do something like:

for (var i=0, len = jImages.length; i< len; i++)

answered Oct 29, 2013 at 14:13

ProGM

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