Algorithm To Break Down Item For Chrome Storage Sync

I am trying to save a string (correction: it is an object containing multiple strings of varying sizes) using chrome.storage.sync.set but am receiving the error: Error: QUOTA_BYTES

Solution 1:

Writing: generate an object like {foo0: chunkA, foo1: chunkB, foo2: chunkC, foo#: 3}.

function chunkedWrite(key, value) {
  return new Promise(resolve => {
    if (typeof key !== 'string') key = `${key}`;
    const str = JSON.stringify(value); // consider using LZString's compressToUTF16
    const len = chrome.storage.sync.QUOTA_BYTES_PER_ITEM - key.length - 4;
    const num = Math.ceil(str.length / len);
    const obj = {};
    obj[key + '#'] = num;
    for (let i = 0; i < num; i++) {
      obj[key + i] = str.substr(i * len, len);
    }
    chrome.storage.sync.set(obj, resolve);
  });
}

Reading is two-part: read the number of keys first, then read all the keys at once.

function chunkedRead(key) {
  return new Promise(resolve => {
    if (typeof key !== 'string') key = `${key}`;
    const keyNum = key + '#';
    chrome.storage.sync.get(keyNum, data => {
      const num = data[keyNum];
      const keys = [];
      for (let i = 0; i < num; i++) {
        keys[i] = key + i;
      }
      chrome.storage.sync.get(keys, data => {
        const chunks = [];
        for (let i = 0; i < num; i++) {
          chunks.push(data[key + i] || '');
        }
        const str = chunks.join('');
        resolve(str ? JSON.parse(str) : undefined);
      });
    });
  });
}

Deleting is similar to reading: read key#, then delete the array of keys.

function chunkedDelete(key) {
  return new Promise(resolve => {
    if (typeof key !== 'string') key = `${key}`;
    const keyNum = key + '#';
    chrome.storage.sync.get(keyNum, data => {
      const num = data[keyNum];
      const keys = [keyNum];
      for (let i = 0; i < num; i++) {
        keys.push(key + i);
      }
      chrome.storage.sync.remove(keys, resolve);
    });
  });
}