bulkAdd-logicalAdd-singleTrans.js

/**
* Here also, all objects are added in a single transaction, with the difference being, before addition,
* the object is checked for equality. If same object exists, then update is performed, otherwise addition is proceeded.
*/
connection.onsuccess = (e) => {
    var db = e.target.result;
    let startedTime = Date.now();
    console.log(`Started on - ${startedTime}`);
    var transaction = db.transaction('contacts', 'readwrite');
    var store = transaction.objectStore('contacts');
    var newContactsToAdd = contacts;
    var allContactsReq = store.getAll();
    allContactsReq.onsuccess = (evt) => {
        const existingContacts = evt.target.result;
        const commonContactIds = [];
        var updateTrans = db.transaction('contacts', 'readwrite');
        var updateStore = updateTrans.objectStore('contacts');
        var deleteTrans = db.transaction('contacts', 'readwrite');
        var deleteStore = deleteTrans.objectStore('contacts');
        existingContacts.forEach(contact => {
            // Check if the same contact is in the new contacts list
            const cIndex = newContactsToAdd.findIndex(c => c.id === contact.id);
            if (cIndex >= 0) {
                const contactToUpdate = newContactsToAdd.splice(cIndex, 1);
                const req = updateStore.put(contactToUpdate, 'id');
                req.onerror = (evt) => {
                    console.log(`Error  on updating contact`);
                    evt.preventDefault();
                };
                req.onsuccess = (evt) => {
                    console.log(`Update Timestamp - ${Date.now()}`);
                };
                commonContactIds.push(contactToUpdate.id);
            }else {
                // These contacts will have to be removed
                console.log('Id to delete -' + contact.id);
                const req = deleteStore.delete(contact.id);
                req.onerror = (evt) => {
                    console.log(`Error on deleting contact`);
                    evt.preventDefault();
                };
                req.onsuccess = (evt) => {
                    console.log(`Delete Timestamp - ${Date.now()}`);
                };
            }
        });
        // Add new contacts
        newContactsToAdd.forEach(contact => {
            const req  = updateStore.add(contact, contact.id);
            req.onerror = (evt) => {
                console.log(`Error on adding contact`);
                evt.preventDefault();
            };
            req.onsuccess = (evt) => {
                console.log(`Add Timestamp - ${Date.now()}`);
            };
        });

    };
    allContactsReq.onerror = (evt) => {
        console.log(`Could not fetch exisitng contacts`);
        store.clear();
        // Add all contacts
    };
};