Not able to fetch values from two dimensional array in Javascript

Question

I am inserting values in two dimensional array according to my role_id i.e

var tdarray = [[]]; 
tdarray[40].push(22);

where 40 is my role_id and 22 is its value. However when i print this value it shows null

alert(tdarray[40][0]); //this shows no value.

I guess two dimensional array in jquery does not allow to insert values at specific position.Can you suggest me what i can do to overcome this. Entire Code is here

var tdarray = [[]];
var incr = 1;
var check;
$(function () {
    $('.toggle_checkbox').change(function () {
        if (check === null) {} else {
            if (this.name == check) {
                incr++;
            } else {
                incr = 1;
            }
        }
        var tval = $(this).val();
        check = this.name;
        tdarray[this.name].push(tval);
    });
});

Html code

<table border = "0"
cellspacing = "0"
cellpadding = "1" >
    <tbody>
               <c:forEach items="${accessRightValues}" var="rights" >
        <tr style="height: 40px;">
            <td style="width: 240px;"><input type="checkbox" name="<c:out value="${rights.roleid}"/>" value="1" class="toggle_checkbox"> Add </td>
            <td style="width: 240px;"><input type="checkbox" name="<c:out value="${rights.roleid}"/>" value="2" class="toggle_checkbox">Update</td>
            <td style="width: 240px;"><input type="checkbox" name="<c:out value="${rights.roleid}"/>" value="3" class="toggle_checkbox">View </td>
             <td style="width: 240px;"><input type="checkbox" name="<c:out value="${rights.roleid}"/>" value="4" class="toggle_checkbox">Delete </td>
            <td style="width: 240px;"><input type="checkbox" name="<c:out value="${rights.roleid}"/>" value="5" class="toggle_checkbox">Assign </td>
        </tr>

        </c:forEach>   

        </tbody> < /table>

My problem is that id 40 can hold more than one value .So i want to know how i can do it using multidimensional array in jquery.Also there can be more than one role_id's such as 50,57 which will again hold more than one value.Please help me regarding the same. I want to pass this two dimensional array in my spring controller. tdarray[40][0] =1; tdarray[40][1] =3; tdarray[40][2] =5; tdarray[48][0] =2; tdarray[48][1] =3;

where 40,48 is role_id of a user and 1,3,5 are access_rights which i want to store in database.

Can you add more details about your 2 dimensional array. tdarray[40].push(22); in this code nothing is related to jquery — Sandeeproop
– Sandeeproop, Commented Jul 8, 2015 at 9:39
Technically this is a pure javascript feature (not truly a jQuery feature), and you are doing it in the wrong way: In a nutshell, because 40 is a numeric key, you have to first declare that index as an array: tdarray[40] = []; and then push a value inside it : tdarray[40].push(22); . That said, your array should be declared as: var tdarray = [];. And, finally, I would rather recommend you an object for such a scope: var tdobject = {}; tdobject[40] = [22]; jsfiddle.net/ok96wwyf — briosheje
– briosheje, Commented Jul 8, 2015 at 9:43
Perhaps give us an example of what you want to do with the data and we can suggest a good JS solution. — stevenw00
– stevenw00, Commented Jul 8, 2015 at 9:43
var tdarray = [[]]; is not a multi-dimensional array. It's an array with one element which is another (empty) array; Your next line with push throws exception because tdarray[40] is undefined. You have to do tdarray[40] = [22];. Later on you can push new values tdarray[40].push(23); and this will become a md array — Kirill Slatin
– Kirill Slatin, Commented Jul 8, 2015 at 9:44
After the edit, you can either use an object or just add: tdarray[this.name] = tdarray[this.name] instanceof Array ? tdarray[this.name] : []; before: tdarray[this.name].push(tval);. This will check if tdarray[this.name] is an array. If so, it just let it be and push the next value inside it, else it will initialize it as an array. — briosheje
– briosheje, Commented Jul 8, 2015 at 9:48

nanndoj · Accepted Answer · 2015-07-08 11:29:16Z

3

In order to use push() function in the key 40 you have to initialize that position as an array as well.

var tdarray = []; 
tdarray[40] = [];
tdarray[40].push(22)

// It works now
alert(tdarray[40][0]);

In the code you provided:

    var tdarray = [];

    ... 

    // Check if it's an array before initialize
    if(!tdarray[this.name] instanceof Array) {
        tdarray[this.name] = []; // or tdarray[this.name] = new Array();
    }
    tdarray[this.name].push(tval);

edited Jul 8, 2015 at 11:29

answered Jul 8, 2015 at 9:44

nanndoj

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3 Comments

Luis Tellez Over a year ago

You need to check if it already have a value or have been initialized first before assigning a new array.

user2975902 Over a year ago

@nanndoj-Its working but my problem is that 40 can hold more than one value in that case how can i assign it i.e tdarray[40][0]=5, tdarray[40][1]=4,

nanndoj Over a year ago

Updated my answer to check if the array is initialized before. so it can accept more values

Desi Cochrane · Accepted Answer · 2015-07-08 09:48:22Z

0

Maybe obvious solution, but if you want to be able to access your values by a key (such as 40), why not use an object?

var tdarray = {};

if ( ! tdarray['40']) tdarray['40'] = [];
tdarray['40'].push(22)

edited Jul 8, 2015 at 9:48

answered Jul 8, 2015 at 9:41

Desi Cochrane

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Comments

Luis Tellez · Accepted Answer · 2015-07-08 09:50:33Z

0

You have to check if its an array already and if its not create it.

var tval = $(this).val();
       check=this.name;
if( tdarray[this.name]constructor !== Array){
 tdarray[this.name]=[]
}
          tdarray[this.name].push(tval);

answered Jul 8, 2015 at 9:50

Luis Tellez

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