localstorage-ext

Frontend localStorage Extension

This library provides tools on how to:

• Check if localStorage is supported
• Check if localStorage has an Item
• Get the amount of space left in localStorage
• Get the maximum amount of space in localStorage
• Get the used space in localStorage
• Get a Backup of localStorage
• Apply a Backup to localStorage
• Dump all information of localStorage in the console

Example

console.log('LocalStorage supported:', LocalStorage.isSupported)
// true https://caniuse.com/#search=localstorage (except Opera Mini)

if(LocalStorage.isSupported) {

    localStorage.setItem('asd', 'ASDASD')
    // sets or overwrites the item "asd"

    var backup = LocalStorage.getBackup()
    // creates an backup, we will need it later!

    console.log(JSON.stringify(backup))
    // this is how the backup looks like

    // The maximum storage-space possible in my tests: ~5MB
    //  - 5242880 Chrome, Firefox
    //  - 5000000 Edge, IE

    var usedSpace = LocalStorage.getUsedSpace()
    console.log('Used Space:', usedSpace)

    var maxSpace = LocalStorage.getMaximumSpace()
    console.log('Maximum Space:', maxSpace)

    var remSpace = LocalStorage.getRemainingSpace()
    console.log('Remaining Space:', remSpace)

    console.log('SpaceCheck', maxSpace === usedSpace + remSpace)
    // true 😉

    console.log('hasItem', LocalStorage.hasItem('nothis0ne'))
    // we don't have this one in our localStorage

    localStorage.clear()
    // oops, we deleted the localStorage!

    console.log('has asd', LocalStorage.hasItem('asd'))
    // item "asd" is lost 😒

    LocalStorage.applyBackup(backup)
    // but we have a backup, restore it!

    LocalStorage.consoleInfo()
    // show all the info we have, see the backup worked 😊
}

FAQ

• [link] How to store Objects or Arrays in localStorage *
• [link] How to store an Array in localStorage *
• [link] How to save an Image in localStorage
• [link] localStorage Tutorial (also covers storage events and things to remember)

* Spoiler: Use JSON.stringify() and JSON.parse()

Other

• [link] General Information about Web Storage
• [link] sessionStorage data stored gets cleared when the page session ends
• [link] indexedDB a low-level API for client-side storage of structured data
• [link] StackOverflow post