checkbox is checked if value is in database in php using jquery

i want to checkde the checkbox if its value is found in the database. for that i have two array one is checkbox array and another is result of database so, compare both and when match is found then checkde the checkbox.

$('body').on('click','.update', function(){
                    var edit_id = $(this).attr('id');
                    
                    var a=[];
                    var b=[];
                    $.ajax({
                        type: 'POST',
                        url: 'update.php',
                        data: 'edit_id='+edit_id,
                        success: function(data) {
                                                   
                          
                            var a=data.split(",");
                           $("#up").val(a[0]);
                           $("#title1").val(a[1]);
                           $("#prod").val(a[2]);
                           $("#dir").val(a[3]);
                           $("#wri").val(a[4]);
                          
                           
                       
                          var c = (a[5]);
                          var b=c.split(".");
                                                    
                           var g=document.getElementsByName("genre[]");
                           for(var i=0;i<g.length;i++)
                           {    
                           var t=document.getElementsByName("genre[]")[i].value;
                           document.getElementsByName("genre[]")[i].checked=false ;
                            
                            if(t[i]=b[i])
                            {
                                document.getElementsByName("genre[]")[i].checked=true ;
                              //$(t[i]).prop("checked", true);
                            }
                             
                           }
                        
                       //rowElement.add("<tr>" + data + "</tr>");
                       //$('#chatbox table tr:last').after("<tr>" + data + "</tr>");
                            if (data = "true") {
                                // $("#title1").val(data);
                                alert("update "+data);
                                
                                 }
                            else {
                                alert("not update");
                               alert("update"+data[0]);
                                }
                                
                        }
                        
                     });
           
                 });