[PWA] 12. Intro to IndexedDB

Posted 2020-07-07 Answer1215

Use the library indexedDB-promised.

 

Create a database and stroe:

import idb from \'idb\';

// Open(db_name, version, cb)
var dbPromise = idb.open(\'test-db\', 1, function (upgradeDb) {
    var keyValStore = upgradeDb.createObjectStore(\'keyval\'); // create table
    //put(value, key)
    keyValStore.put(\'world\', \'Hello\');
});

Notice put() function take value frist then key.

 

Read the key in stroe:

// read "hello" in "keyval"
dbPromise.then(function (db) {
    var tx = db.transaction(\'keyval\'); // Open a transaction
    var keyValStore = tx.objectStore(\'keyval\'); // read the store
    return keyValStore.get(\'hello\'); // get value by key
}).then(function (val) {
    console.log(\'The value of "hello" is:\', val);
});

 

Write value to store:

// set "foo" to be "bar" in "keyval"
dbPromise.then(function (db) {
    var tx = db.transaction(\'keyval\', \'readwrite\'); // ready for add key value
    var keyValStore = tx.objectStore(\'keyval\'); // get the store
    keyValStore.put(\'bar\', \'foo\'); // set the value, notice it may not be success if any step in transaction fail.
    return tx.complete; // tx.complete is a promise
}).then(function () {
    console.log(\'Added foo:bar to keyval\');
});