Simple Request: Uncaught TypeError: Cannot read property 'length' of undefined

Question

I am using a simple JSON Ajax request to get some JSON data. But all the time I try to use the JSON object I get the following issue:

Uncaught TypeError: Cannot read property 'length' of undefined

$(document).on('pageinit', '#home', function() {
    $.ajax({
        url: "http://localhost/documents.json",
        dataType: "json",
        type: 'GET',
        async: true,
        success: function(result) {
            //ajax.parseJSON(result);
            $.each(result, function(idx, obj) {
                alert(obj.name);
            });
        },
        error: function(request, error) {
            alert('Network error has occurred please try again!' + ' ' + request + ' ' + error);
        }
    });
});

my JSON file is valid and looks like that:

{
  "books": [{
    "id": "01",
    "name": "info",
    "dateiname": "info.pdf"
  }, {
    "id": "02",
    "name": "agb",
    "dateiname": "agb.pdf"
  }, {
    "id": "03",
    "name": "raumplan",
    "dateiname": "raumplan.pdf"
  }, {
    "id": "04",
    "name": "sonstiges",
    "dateiname": "sonstiges.pdf"
  }, {
    "id": "05",
    "name": "werbung",
    "dateiname": "werbung.pdf"
  }]
}

Answer 1

You should perform something like the following:

if(result && result["books"]) {
    $.each(result["books"], function(idx, obj) {
        alert(obj.name);
    });
}

Answer 2

jQuery.each can make this error if you provide a undefined value. But result can't be undefined or jQuery would throw a JSON parse error. At least result is an empty object {} (or an empty array [] ).

Your code never read the length of anything. So i assume your error is somewhere else in your code.

Double check the error in your console. You should have the exact line of the error. And the stack too.

But there's still an error in your code. You should have this :

$.each(result.books, function(idx, obj) {
    alert(obj.name);
});