Getting the length of an array inside another array,

Question

I am coding an ajax live search box and the returned row could come from two separate MySQL tables. I need to figure out what table the data has come from. For that i figured, as table1 has three columns and table2 has five, i can count the number of elements in the returned array and then i will know.

But MySQL query needs to return the top three entries, hence i am getting an array which always has three elements, which are again arrays.

I need to count the number of elements in the internal array.

How would i do that?

I tried the following, it doesn't work:

$('#search').keyup(function(e) {
  $('#results').empty();
  if ($(this).val().length > 2) {
    $.get('php/search.php', {
      input: $(this).val()
    }, function(data) {
      res = $.parseJSON(data);
      //check if returned data is customer row or vehicle row by counting elements
      //customer row will have 3, vehicle will have 5
      //var x = res[0].length;
      for (var i = 0; i < res.length; i++) {
        var a = "<h2 class=\"searchcustomer\" id=\"result" + i + "\">" + res[i]['name'] + " " + res[i]['mobile'] + "</h2>";
        $('#results').append(a);
        //alert('Its customer'); 
      };
    });
  };
});

The return from the server file is:

[{
  "id": "1",
  "cusid": "4",
  "make": "Hyundai",
  "model": "I10",
  "registration": "DL23IK4837"
}, {
  "id": "2",
  "cusid": "4",
  "make": "Maruti",
  "model": "Swift",
  "registration": "DL87UU8933"
}, {
  "id": "3",
  "cusid": "6",
  "make": "Mitsubishi",
  "model": "Lancer",
  "registration": "DL22NM4435"
}]

@mplungjan apologies, but thanks for doing it for me. I clicked on edit to do it, and then saw it was all done. Was wondering how. — notANerdDev
– notANerdDev, Commented May 13, 2015 at 11:59

Realitätsverlust · Accepted Answer · 2015-05-13 12:48:42Z

2

You are using length on object, it will be undefined always. You should use Object.keys instead.

var x = Object.keys(res[0]).length; //this is working

You have many syntax errors in the code above:

$('#search').keyup(function(e) {
$('#results').empty();
if ($(this).val().length > 2) {
    $.get('php/search.php',
        {
            input: $(this).val(), cusid: 0
        },
        function(data) {
            res = $.parseJSON(data);

            // check if returned data is table1 or table2 by counting elements
            // table1 will have 3, table2 will have 5

            var x = Object.keys(res[0]).length; //this is working
            //      ^^^^^^^^^^^^^^^^^^^^^^^^^^
            alert(Object.keys(res[0]).length);
            if (x == 3) {
                // respective code
            }
            else if (x == 5) {
                // respective code
            }
        });
}

});

Using $x to get data and x in if conditions
; should not be used for if else
Missing ) of get

Demo: https://jsfiddle.net/tusharj/Loevj0tL/

edited May 13, 2015 at 12:48

Realitätsverlust

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answered May 13, 2015 at 11:28

Tushar

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7 Comments

notANerdDev Over a year ago

Yeah... I actually pasted the code and then edited it in the browser..Let me fix what i can spot again and then edit it here.

Tushar Over a year ago

@user3324298 Show the data returned from server

notANerdDev Over a year ago

Great thanks! I actually saw this somewhere else in another help website, but i guess i didn't use it properly that time. This works!

mplungjan Over a year ago

How would the valid array have a length of 0? This alerts 3:

res = $.parseJSON('[{  "id": "1",  "cusid": "4",  "make": "Hyundai",  "model": "I10",  "registration": "DL23IK4837"}, {  "id": "2",  "cusid": "4",  "make": "Maruti",  "model": "Swift",  "registration": "DL87UU8933"}, {  "id": "3",  "cusid": "6",  "make": "Mitsubishi",  "model": "Lancer",  "registration": "DL22NM4435"}]') alert(res.length)

notANerdDev Over a year ago

@mplungjan The valid array does have a length of 3. Where did anyone say otherwise? I needed the length of the first element in the array. So not res.length, but length of res[0].

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