check localStorageSpace

localStorageSpace.js

var localStorageSpace = function(){
    var data = '';
    
    for(var key in window.localStorage) {
        
        if(window.localStorage.hasOwnProperty(key)) {
            
            data += window.localStorage[key];
            console.log(key + ' = ' + ((window.localStorage[key].length * 16) / (8 * 1024)).toFixed(2) + ' KB');
            
        }
        
    }
    
    console.log(data ? '\n' + 'Total space used: ' + ((data.length * 16)/(8 * 1024)).toFixed(2) + ' KB' : 'Empty (0 KB)');
    console.log(data ? 'Approx. space remaining: ' + (5120 - ((data.length * 16)/(8 * 1024)).toFixed(2)) + ' KB' : '5 MB');
    
};