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I've got an object that represents playlist in my extension and I need to save it to chrome.storage.sync.

I know about 4096 QUOTA_BYTES_PER_ITEM, that means key.length + JSON.stringify(val).length must be less than 4096. but my object is 3956 (val stringify length + ket length), and I still can't write it to the storage. What am I doing wrong?

My object JSON stringification result:

{"playlist":{"state":{"tracks":[{"artist":"In Flames","title":"Delight And Angers (Instrumental)"},{"artist":"Marilyn Manson","title":"Coma Black"},{"artist":"Red Hot Chili Peppers","title":"Can't Stop"},{"artist":"Jack Johnson","title":"Better Together (Hawaiian Version)"},{"artist":"Joel Nielsen","title":"Surface Tension 2"},{"artist":"Katatonia","title":"Deliberation"},{"artist":"Rev Theory","title":"Hell Yeah"},{"artist":"Die drei Friseure ","title":"Parikmaher"},{"artist":"In Flames","title":"Drenched in Fear"},{"artist":"In Flames","title":"A New Dawn"},{"artist":"Before The Dawn","title":"The First Snow/Winter Within"},{"artist":"Corey Taylor & James Root","title":"Zzyzx Road"},{"artist":"In Flames","title":"Ropes"},{"artist":"In Flames","title":"Come Clarity"},{"artist":"Jack Johnson","title":"Better Together"},{"artist":"In Flames","title":"Crawl Through Knives"},{"artist":"Ленинград","title":"День Рождения.а я вот день рожденье не буду справлять!"},{"artist":"Ellen McLain","title":"Still Alive"},{"artist":"Richard Cheese","title":"People Equals Shit "},{"artist":"Papa Roach","title":"Last Resort"},{"artist":"Killswitch Engage","title":"The End of Heartache"},{"artist":"Sonic Syndicate","title":"Denied"},{"artist":"Trivium","title":"Pull Harder On The Strings Of Your Martyr"},{"artist":"Bon Jovi","title":"Last Man Standing"},{"artist":"Jelonek","title":"Beast"},{"artist":"Gorillaz","title":"Feel Good Inc"},{"artist":"Five Finger Death Punch","title":"Falling In Hate"},{"artist":"Metallica","title":"The Memory Remains (Live)"},{"artist":"Richard Z. Kruspe","title":"Wake up"},{"artist":"Nylithia","title":"Infector (Intro)"},{"artist":"Nylithia","title":"Super Mario B Castle Theme"},{"artist":"Scorpions/Скорпионс","title":"Wind Of Change/Ветер Перемен  (Версия на русском языке)"},{"artist":"Michael Andrews","title":"Mad World"},{"artist":"John 5","title":"2 Die 4"},{"artist":"Escape the Fate","title":"This War Is Ours (The Guillotine Part II)"},{"artist":"John 5","title":"Damaged"},{"artist":"Marty Friedman","title":"Dragon Mistress"},{"artist":"Pelican","title":"The Creeper"},{"artist":"JELONEK","title":"BaRock"},{"artist":"Blotted Science","title":"Laser Lobotomy"},{"artist":"The String Quartet Tribute  to NIRVANA","title":"Come As You Are "},{"artist":"String Tribute","title":"Tears Don't Fall (BFMV)"},{"artist":"Papa Roach","title":"Change or Die"},{"artist":"Trivium","title":"Dying in your arms"},{"artist":"Disturbed","title":"Decadance"},{"artist":"Bullet For My Valentine","title":"Turn To Despair"},{"artist":"Metallica","title":"Orion [Instrumental]"},{"artist":"Divination","title":"The Heretic Anthem"},{"artist":"Bullet for my Valentine","title":"Say Goodnight (Acoustic Version)"},{"artist":"Кувалда","title":"Бетономешалка"},{"artist":"Slipknot","title":"Confessions"},{"artist":"Bullet For My Valentine","title":"7 Days (Bonus Track)"},{"artist":"Bullet for My Valentine","title":"Forewer and Always (Acoustic Version)"},{"artist":"Bullet For My Valentine","title":"Hearts Burst Into Fire (Acoustic Version)"},{"artist":"In Flames","title":"Everlost (Part II)"},{"artist":"In Flames","title":"Acoustic Medley"},{"artist":"In Flames","title":"Cloud Connected"},{"artist":"In Flames","title":"Crawl Through Knives"},{"artist":"In Flames","title":"Free Fall"},{"artist":"Metallica","title":"Die, Die My Darling"},{"artist":"Slipknot","title":"Psychosocial (Album Version)"},{"artist":"Korn","title":"Jingle Bells"},{"artist":"Stone Sour","title":"Through Glass"},{"artist":"Slipknot","title":"Snuff"},{"artist":"Звонок в компанию Microsoft","title":"Как крякнуть Висту?"},{"artist":"Furious Ball","title":"Fog"},{"artist":"The Beatles","title":"Yellow Submarine"},{"artist":"Lumen","title":"Космонавт"},{"artist":"Lumen","title":"Государство"},{"artist":"Bullet For My Valentine","title":"Tears Don't Fall (Acoustic) (Bonus Track)"},{"artist":"Karunesh","title":"The Wanderer "}],"currentTrack":0}}}

the following code calculates my object size to be stored in storage:

for(var i in obj) {
    console.log(i, JSON.stringify(obj[i]).length + i.length)
}

and it returns

> playlist 3956

I can't understand that, maybe such kind of magic because of UTF-8 non latin symbols in my object? Maybe chrome on native side performs escaping (\uXXXX) of this characters and got more than 4096 length? If so, how can I get JSON.stringify() to also do that escaping?

Rob W
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Titenko Stanislav
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2 Answers2

3

chrome.storage.sync.QUOTA_BYTES_PER_ITEM specifies the maximum size in bytes. In Chrome, JavaScript strings are encoded as UTF-8. A UTF-8 "character" has a variable byte length, it is either 1 or 2.

Your string contains "Бетономешалка". The string length is 13, but the byte size is 26.

To detect the size of a character, you could use string.charCodeAt(index) to get the character code of the string at a specified index. If this number is smaller than 256 (<= 0xFF), then it consists of one byte. Otherwise it will have two bytes.
Some other ways to count the number of bytes in a string are listed at How many bytes in a JavaScript string?.

Community
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Rob W
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0
/**
 * Count bytes in a UTF-8 string's representation.
 *
 * @param {string}
 * @return {number}
 */
function byteLength(str) {
    str = String(str); // force string type
    return (new TextEncoder('utf-8').encode(str)).length;
}
holmberd
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