browserSettings.cacheEnabled

function logResult(result) {
  console.log(`Current value: ${result.value}`);
  console.log(`Current level of control: ${result.levelOfControl}`);
}

browser.browserSettings.cacheEnabled.get({}).then(logResult);

function logResult(result) {
  console.log(`Setting was modified: ${result}`);
}

browser.browserSettings.cacheEnabled.set({ value: false }).then(logResult);