iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Wrap both the window.localStorage lookup and each storage operation in try...catch. The lookup can throw before a method runs, and a write can fail even after storage is obtained. Treat persistence as optional when possible: keep the app working with its current in-memory or default value, and tell users when a failed save matters to them.
Why localStorage errors happen
There are two important failure points. The browser may reject access to the storage object itself, or it may reject a particular write. The WHATWG HTML Standard’s Web Storage section describes both exceptions.
Accessing the storage object can throw SecurityError
Evaluating window.localStorage can throw a SecurityError when the document has an opaque origin or a browser policy does not allow the page to persist data. MDN also identifies invalid schemes such as file: and data:, and browser settings that block persistence, as relevant cases. Because the getter itself can fail, putting only getItem() or setItem() in a try block is not enough. See the MDN localStorage reference.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
A write can throw QuotaExceededError
Storage.setItem() throws QuotaExceededError if the new value cannot be set. The standard gives examples including exceeded quota and storage being disabled. The exception name alone does not tell you which condition occurred: MDN notes that a storage area can be unavailable even when the issue is not simply that existing data filled it. There is no fixed cross-browser quota established here, so avoid promising a universal byte or megabyte limit. Consult the standard and MDN’s storage quota and eviction guidance for current browser-specific considerations.
#1 Best Overall
- USB-C 2-in-1 storage OTG: The Lexar JumpDrive Dual Drive D40E features USB Type-A and Type-C connectors in a slim, portable form factor for easy device compatibility
- Transfer speeds up to 100MB/s: Based on internal testing, performance may vary depending upon the host device, interface, and usage conditions. 1MB=1,000,000 bytes
- Plug and Play: Widely compatible with USB Type-C smartphones, tablets, laptops, Macs, and traditional Type-A devices, no software installation required. The 360° swivel design allows for easy switching between connectors without the hassle of losing a cap
- Durable & Compact: The Lexar D40E USB memory stick features a metal enclosure, withstands temperatures from 0° to 50° C (32°F to 122°F), and is lightweight at 26g with dimensions of 70.4 x 16.9 x 11.7mm
- Security & Warranty: Securely protects files using an advanced security software solution with 256-bit AES encryption. Backed by a Lexar 3-year limited warranty
Protect the getter and the operation
Keep the storage lookup inside the same protected block as the operation. This example returns a success flag so callers do not mistake a failed write for a saved value:
function savePreference(key, value) {
try {
window.localStorage.setItem(key, value);
return true;
} catch (error) {
// The app can continue using its current in-memory value.
return false;
}
}Handle the result where the application knows whether persistence matters:
Rank #2
- High-speed USB 3.0 performance of up to 150MB/s(1) [(1) Write to drive up to 15x faster than standard USB 2.0 drives (4MB/s); varies by drive capacity. Up to 150MB/s read speed. USB 3.0 port required. Based on internal testing; performance may be lower depending on host device, usage conditions, and other factors; 1MB=1,000,000 bytes]
- Transfer a full-length movie in less than 30 seconds(2) [(2) Based on 1.2GB MPEG-4 video transfer with USB 3.0 host device. Results may vary based on host device, file attributes and other factors]
- Transfer to drive up to 15 times faster than standard USB 2.0 drives(1)
- Sleek, durable metal casing
- Easy-to-use password protection for your private files(3) [(3)Password protection uses 128-bit AES encryption and is supported by Windows 7, Windows 8, Windows 10, and Mac OS X v10.9 plus; Software download required for Mac, visit the SanDisk SecureAccess support page]
const saved = savePreference("theme", "dark");
if (!saved) {
// Keep the selected theme for this session, and notify the user
// if they expect the preference to survive a reload.
}If you need to obtain storage separately, protect the getter itself:
Recommended Free Tools
function getLocalStorage() {
try {
return window.localStorage;
} catch {
return null;
}
}A returned storage object does not guarantee that later writes will succeed. Continue to catch errors around operations such as getItem(), setItem(), and removeItem() at the point where your code calls them.
Rank #3
- What You Get - 2 pack 64GB genuine USB 2.0 flash drives, 12-month warranty and lifetime friendly customer service
- Great for All Ages and Purposes – the thumb drives are suitable for storing digital data for school, business or daily usage. Apply to data storage of music, photos, movies and other files
- Easy to Use - Plug and play USB memory stick, no need to install any software. Support Windows 7 / 8 / 10 / Vista / XP / Unix / 2000 / ME / NT Linux and Mac OS, compatible with USB 2.0 and 1.1 ports
- Convenient Design - 360°metal swivel cap with matt surface and ring designed zip drive can protect USB connector, avoid to leave your fingerprint and easily attach to your key chain to avoid from losing and for easy carrying
- Brand Yourself - Brand the flash drive with your company's name and provide company's overview, policies, etc. to the newly joined employees or your customers
Choose a fallback that matches the feature
Decide what the user should experience if persistence is unavailable before choosing how visible the failure should be.
- Optional preference: Keep the selected value in application memory and use a sensible default on a fresh page load. A failed save may not need an interruption if the user does not expect the choice to persist.
- Important saved state: Do not claim that the change was saved. Return a failure result or show a concise notice explaining that it will not survive a reload, while preserving the current session state if feasible.
- Data the feature depends on: If losing persistence would make the feature unusable or risk user data, provide a deliberate recovery or alternate storage path rather than silently carrying on as though the write succeeded.
Keep recovery narrow. Automatically calling localStorage.clear() to make room deletes every key/value pair for the origin, not just the item that failed. Do not do this without a clear product reason and an appropriate user expectation.
Rank #4
- GOOD VALUE PACKAGE - 1 Pack 32GB Memory Stick USB 2.0 Flash Drives with great cost performance and high quality.
- BIG CAPACITY - The available capacity: 29.10GB-29.8GB, You can save the data of movies, music, photos, designs, programs, manuals, handouts in a high speed.Good performance in digital data storing, transferring and sharing with families, friends, workmates, clients and machines.
- EASY TO USE & PLUG AND WORK - Support windows 7 / 8 / 10 / Vista / XP / 2000 / ME / NT Linux and Mac OS, Compatible with USB2.0 and below.
- TWISTTURN DESIGN & EASY CARRY - The metal clip rotates 360° round the ABS plastic body which with rubber oil skin feeling finish. The capless design can avoid lossing of cap, and providing efficient protection to the USB port.
- WARRANTY & SUPPORT - SIMMAX logo is laser printed on the USB connector surface, our products are of good quality and we promise that any problem about the product within one year since you buy.
Check the page context before diagnosing the failure
Local storage is separated by origin and protocol: the HTTP and HTTPS versions of a site do not share the same storage object. Test the actual deployed origin rather than assuming that a different development or preview URL behaves the same way. Behavior for file: documents is undefined by the standard and can vary between browsers.
When access fails, check whether the page is served over HTTP(S), whether it is running in a sandboxed or otherwise opaque-origin context, and whether browser policy or user settings prohibit persistence. Private-session data is cleared when the last private tab closes, and browser policy can prevent persistence more broadly. Do not make weakening privacy settings the default fix; the app should handle unavailable persistence gracefully.
Best Value
- 【16GB Flash Drive】USB flash drives with 16GB capacity, meet your needs of daily use on work, school, home and travelling for photos, music, videos, files storage and transfer. IMEASON thumb drives can be used to store different files, easy to data backup.
- 【Metal Swivel Cap Design】USB thumb drive is metal swivel cover provides extra protection for the usb thumbdrive connector, no usb drive cap to lose; keychain design makes it easier to carry without worrying lose it.
- 【Wide Compatibility】USB drive supports Windows 7/8/10/11 / Vista / XP / Unix / 2000 / ME / NT Linux and Mac OS, also Supports USB 2.0 and 1.1 ports. USB Stick support TV, desktop, notebook computer, car, audio and other device. The USB Memory Stick is your great data storage and transfer companion with traveling and working.
- 【Easy to use】usb memory stick is plug and play without any software installation. Just simply plug the Flashdrive into the port of your USB-compatible devices such as computer, laptop to start data storage or transmission.
- 【What You Get】16 GB USB Flash Drive Thumb Drive, The default format of the usb storage flash drive is FAT32.
Use an availability probe only when you need one
A probe can test more than the getter: obtain the storage object, write a temporary key, and remove it, all inside protected handling. MDN’s availability example accounts for the case where QuotaExceededError occurs but storage already contains data. If adapting that approach:
- Use a collision-resistant temporary key so you do not overwrite an application value.
- Remove the temporary key after a successful write, and handle cleanup failures too.
- Remember that the probe writes to the user’s storage area; do not run it repeatedly without a reason.
- Treat the result as a check at that moment, not a guarantee that a later application write will succeed.
Keep localStorage workloads small
Web Storage is synchronous: reads, writes, and removals block JavaScript execution while they run. That makes it suitable for small preferences, not large, frequent, or structured workloads. If your feature needs more substantial storage, review the browser’s available storage APIs and their current quota and eviction guidance rather than treating localStorage as an unlimited database. MDN covers these behaviors in its Web Storage API overview and storage quota and eviction criteria.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →
