How to free up memory when saving images inside IndexDB - angularjs-directive

Question

I have a no of images on page and trying to save it inside IndexDb if it does not exist.
All seems to be working fine and images load up instantly if it exist but looks like browser memory is leaking. It's give some jerk and hang sometime. I m not sure how this can be handle, I have written a directive that looks like this
(function () {
'use strict';
// TODO: replace app with your module name
angular.module('app').directive('imageLocal', imageLocal);
imageLocal.$inject = ['$timeout', '$window', 'config', 'indexDb'];
function imageLocal($timeout, $window, config, indexDb) {
// Usage:
//
// Creates:
//
var directive = {
link: link,
restrict: 'A'
};
return directive;
function link(scope, element, attrs) {
var imageId = attrs.imageLocal;
// Open a transaction to the database
var transaction;
$timeout(function () {
transaction = indexDb.db.transaction(["mystore"], "readwrite");
getImage();
}, 500);
function getImage() {
transaction.objectStore('mystore').get(imageId)
.onsuccess = function (event) {
var imgFile = event.target.result;
if (imgFile == undefined) {
saveToDb(imgFile);
return false;
}
showImage(imgFile);
}
}
function showImage(imgFile) {
console.log('getting');
// Get window.URL object
var url = $window.URL || $window.webkitURL;
// Create and revoke ObjectURL
var imageUrl = url.createObjectURL(imgFile);
element.css({
'background-image': 'url("' + imageUrl + '")',
'background-size': 'cover'
});
}
function saveToDb() {
// Create XHR
var xhr = new XMLHttpRequest(),
blob;
xhr.open("GET", config.remoteServiceName + '/image/' + imageId, true);
// Set the responseType to blob
xhr.responseType = "blob";
xhr.addEventListener("load", function () {
if (xhr.status === 200) {
console.log("Image retrieved");
// Blob as response
blob = xhr.response;
console.log("Blob:" + blob);
// Put the received blob into IndexedDB
putInDb(blob);
}
}, false);
// Send XHR
xhr.send();
function putInDb(blob) {
// Open a transaction to the database
transaction = indexDb.db.transaction(["mystore"], "readwrite");
// Put the blob into the database
var request = transaction.objectStore("mystore").add(blob, imageId);
getImage();
request.onsuccess = function (event) {
console.log('saved');
}
};
}
}
}
})();