arty-local-storage-limit.js

var iterationsData;
var results = document.getElementById('results');

(function () {

if (!('localStorage' in window)) {
    results.innerHTML = 'Your browser has no localStorage support.';
    return;
}

var n10b =    '0123456789';
var n100b =   repeat(n10b, 10);
var n1kib =   repeat(n100b, 10);
var n10kib =  repeat(n1kib, 10);
var n100kib = repeat(n10kib, 10);
var n1mib =   repeat(n100kib, 10);
var n10mib =  repeat(n1mib, 10);

var values = [n10b, n100b, n1kib, n10kib, n100kib, n1mib, n10mib];

iterationsData = [];
for (var majorIndex = 1; majorIndex < values.length; majorIndex++) {
    var major = values[majorIndex];
    var minor = values[majorIndex - 1];
    for (var i = 1; i < 10; i++) {
        for (var j = 0; j < 10; j++) {
            iterationsData.push([major, minor, i, j]);
        }
    }
}

var index = 0;
var oldLength = 0;

function iteration() {
    var data = iterationsData[index];

    major = data[0];
    minor = data[1];
    i = data[2];
    j = data[3];

    var string = repeat(major, i) + repeat(minor, j);
    var length = '' + string.length;

    if (test(string)) {
        results.innerHTML = length + ' characters were stored successfully.';
    } else {
        results.innerHTML = oldLength + ' characters were stored successfully,  but ' + length + ' weren\'t.';
        return;
    }
    oldLength = length;

    index++;
    if (index < iterationsData.length) {
        setTimeout(iteration, 0);
    } else {
        results.innerHTML = oldLength + ' characters were saved successfully, test is stopped.';
    }
}

iteration();

function test(value) {
    try {
        localStorage.test = value;
        return true;
    } catch (e) {
        return false;
    }
}

function repeat(string, count) {
    var array = [];
    while (count--) {
        array.push(string);
    }
    return array.join('');
}

})();