jquery - Not able to fetch values from two dimensional array in Javascript -

i inserting values in 2 dimensional array according role_id i.e

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

where 40 role_id , 22 value. when print value shows null

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

i guess 2 dimensional array in jquery not allow insert values @ specific position.can suggest me can overcome this. entire code 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 id 40 can hold more 1 value .so want know how can using multidimensional array in jquery.also there can more 1 role_id's such 50,57 again hold more 1 value.please me regarding same. want pass 2 dimensional array in 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 role_id of user , 1,3,5 access_rights want store in database.

in order use push() function in key 40 have initialize position array well.

var tdarray = [];  tdarray[40] = []; tdarray[40].push(22)  // works alert(tdarray[40][0]); 

in code provided:

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