localStorage size check (obviously it only works for current domain)

localStorageSize.js

var keys = Object.keys(localStorage);
var total = 0;
for (var i in keys) {
	var key = keys[i];
	var size = localStorage[key].length;
	console.log(key, ' size ', getReadableFileSizeString(size));
	total += size;
}
console.log('\n-------\ntotal size ', getReadableFileSizeString(total));

// 100 -> 100 B
// 512 -> 0.50 kB
function getReadableFileSizeString(fileSizeInBytes) {

    var i = 0;
    var byteUnits = [' B', ' kB', ' MB', ' GB', ' TB', 'PB', 'EB', 'ZB', 'YB'];
	while (fileSizeInBytes > 100) {
        fileSizeInBytes = fileSizeInBytes / 1024;
        i++;
    } 

    return Math.max(fileSizeInBytes, 0.01).toFixed(i > 0 ? 2 : 0) + byteUnits[i];
}