javascript - Adding an index to an existing object store in IndexedDB -

how add index created object store, within upgrade needed event?

doing on new object store documented:

request.onupgradeneeded = function(event) {   var db = event.target.result;   var objectstore = db.createobjectstore("my-store",     { keypath: "id" }   );   objectstore.createindex("idx_name", "index_this", { unique: false }); }; 

but how can add index object store created?

request.onupgradeneeded = function(event) {   var db = event.target.result;   if (!db.objectstorenames.contains("my-store")) {     var objectstore = db.createobjectstore("my-store",       { keypath: "id" }     );   }   var mystore = ?????????????;   if (!mystore.indexnames.contains("idx_name")) {     mystore.createindex("idx_name", "index_this", { unique: false });   } }; 

you want retrieve reference object store transaction implicitly provided within scope of onupgradeneeded function.

function onupgradeneeded(event) {   var request = event.target;   var tx = request.transaction;   var store = tx.objectstore('store-name');   store.createindex(...); } 

keep in mind have rewrite onupgradeneeded function attempt store if has been created, , attempt create index if has not yet been created. there couple of ways of doing that. 1 use version number. can test against old version existed before upgrade, or new/current version. e.g. use event.oldversion if want. alternatively, can test if store exists , separately test if index exists, looking store name using db.objectstorenames.contains, , looking index name in store.indexnames.contains.