//run this in dev console to test how much local storage you have
try {
    // Test up to 20 MB
    for (var i = 250; i <= 20000; i += 250) {
        localStorage.setItem('test', new Array((i * 1024) + 1).join('a'));
    }
} catch (e) {
    localStorage.removeItem('test');
    console.log('Local Storage Max Size is:', (i - 250)/1000, 'MB');            
}