Script para verificar o espaço utilizado no localStorage

localStorageUsedSpace.js

// based on: http://stackoverflow.com/a/17887889/529418
// On Android I get the max 2.5M characters in localStorage (Strings in JavaScript are UTF-16).

var localStorageUsedSpace = function(){
    var allStrings = '';
    for(var key in window.localStorage){
        if(window.localStorage.hasOwnProperty(key)){
            allStrings += window.localStorage[key];
        }
    }
    return allStrings ? 3 + ((allStrings.length*16)/(8*1024)) + ' KB' : 'Empty (0 KB)';
};

var localStorageUsedSpaceBy = function(name){
    var allStrings = '';
    for(var key in window.localStorage){
        if(window.localStorage.hasOwnProperty(key)){
            if (key.indexOf(name) === 0)
                allStrings += window.localStorage[key];
        }
    }
    return allStrings ? 3 + ((allStrings.length*16)/(8*1024)) + ' KB' : 'Empty (0 KB)';
};