check which checkbox is checked

guys i am using jqGrid and i added a column of checkboxes to the grid but i want to alert which checkbox is checked .. here is my code

dataGrid.prototype = {

        display : function() {
                var self = this;
                var html = [];
                var check = 0;
                html.push("<table id='" + this.id + "" + "'class='table'>\n</table>");
                html.push("<div id='pagger_" + this.id + "'></div>");
                $('body').append(html.join(""));
                $("#" + this.id).jqGrid({
                                                        url : "index.jsp",
                                                        styleUI : 'Bootstrap',
                                                        datatype : "local",
                                                        data : this.data,
                                                        colModel : this.getColModels(this.data[0]),
                                                        onSelectRow : this.editRow,
                                                        viewrecords : true,
                                                        width : 1300,
                                                        height : 250,
                                                        rowNum : 50,
                                                        pager : "#pagger_" + this.id,
                                                        loadComplete : function() {
                                                                var iCol = self.getColumnIndexByName('Enable');
                                                                var rows = $("#" + this.id).jqGrid('getGridParam','data');
                                                                var i; 
                                                                var c = rows.length;
                                                                for (i = 0; i < c; i += 1) {
                                                                        $(rows[i].cells[iCol]).click(
                                                                                                        function(e) {
                                                                                                                var id = $(e.target).closest('tr')[0].id, isChecked = $(e.target).is(':checked');
                                                                                                                alert("checked:"+ isChecked);
                                                                                                                // you can also get the
                                                                                                                // values of the row
                                                                                                                // data
                                                                                                        alert('clicked on the checkbox in the row with id='+ id+ '\nNow the checkbox is '+ (isChecked ? 'checked': 'not checked'));
                                                                                                        });
                                                                }
                                                        }

                                                });
        },

        getColNames : function(data) {
                var keys = [];
                for ( var key in data) {
                        if (data.hasOwnProperty(key)) {
                                keys.push(key);
                        }
                }
                return keys;
        },

        getColModels : function(data) {
                var colNames = this.getColNames(data);
                var colModelsArray = [];
                var str2;
                for (var i = 0; i < colNames.length; i++) {
                        var str1;

                        str1 = {
                                name : colNames[i],
                                index : colNames[i],
                                align : 'center',
                                editable : true,
                                edittype : "text",
                        };
                        colModelsArray.push(str1);
                }
                str2 = {
                        name : 'Enable',
                        index : 'Enable',
                        formatter : 'checkbox',
                        editable : true,
                        edittype : 'checkbox',
                        width : 60,
                        align : 'center',
                        formatoptions : {
                                disabled : false
                        },
                        editoptions : {
                                value : '1:0'
                        },
                };
                colModelsArray.push(str2);
                return colModelsArray;
        },

        getColumnIndexByName : function(columnName) {
                var cm = $("#" + this.id).jqGrid('getGridParam', 'colModel'), i, l;
                for (i = 0, l = cm.length; i < l; i += 1) {
                        if (cm[i].name === columnName) {
                                return i;
                        }
                }
                return -1;
        },

};

hint ..

1. the data is json object
2. whenever i print rows[i] it gives me [object object]

Whats wrong here?