javascript - Adding/deleting object properties and removing null -

i trying remember open accordions in custom plugin. first accordion open default, so:

var active = [0]; 

i click on accordions , read localstorage values. inside click event:

var active = json.parse(localstorage.getitem(outername)),     tab = $(this).find('h3').index(ui.tab[0]);  if (tab in active) {     delete active[tab]; } else {     active[tab] = tab; } (var = 0; < this.length; i++) {     if (active[i] == null) {         active.splice(i, 1);         i--;     } } localstorage.setitem(outername, json.stringify(active)); 

this works, except remove first accordion , click second , i'll duplicated values [1,1]. have removed null values each time cause don't know how values if toggle accordion removed object.

[0,3] = accordion 1 , 4 open

[0,1] = accordion 1 , 2 open

ok patched plugin numbers active strings, modified object because broken:

if (tab in active && active[tab] !== null) {     delete active[tab]; } else {     active[tab] = tab; } 

i getting [null,1,null], overwrite null , replace value [0,1,null] , 0 , 1 read plugin.

so answers own questions quickly!