这里有一个简单的脚本来找出限制:

if (localStorage && !localStorage.getItem('size')) {
    var i = 0;
    try {
        // Test up to 10 MB
        for (i = 250; i <= 10000; i += 250) {
            localStorage.setItem('test', new Array((i * 1024) + 1).join('a'));
        }
    } catch (e) {
        localStorage.removeItem('test');
        localStorage.setItem('size', i - 250);            
    }
}

这里是要点，JSFiddle和博客帖子。

该脚本将测试设置越来越大的文本字符串，直到浏览器抛出一个异常。这时，它将清除测试数据，并在localStorage中设置一个大小键，以千字节为单位存储大小。

我将二进制测试压缩到我使用的这个函数中:

function getStorageTotalSize(upperLimit/*in bytes*/) {
    var store = localStorage, testkey = "$_test"; // (NOTE: Test key is part of the storage!!! It should also be an even number of characters)
    var test = function (_size) { try { store.removeItem(testkey); store.setItem(testkey, new Array(_size + 1).join('0')); } catch (_ex) { return false; } return true; }
    var backup = {};
    for (var i = 0, n = store.length; i < n; ++i) backup[store.key(i)] = store.getItem(store.key(i));
    store.clear(); // (you could iterate over the items and backup first then restore later)
    var low = 0, high = 1, _upperLimit = (upperLimit || 1024 * 1024 * 1024) / 2, upperTest = true;
    while ((upperTest = test(high)) && high < _upperLimit) { low = high; high *= 2; }
    if (!upperTest) {
        var half = ~~((high - low + 1) / 2); // (~~ is a faster Math.floor())
        high -= half;
        while (half > 0) high += (half = ~~(half / 2)) * (test(high) ? 1 : -1);
        high = testkey.length + high;
    }
    if (high > _upperLimit) high = _upperLimit;
    store.removeItem(testkey);
    for (var p in backup) store.setItem(p, backup[p]);
    return high * 2; // (*2 because of Unicode storage)
}

它还在测试之前备份内容，然后恢复它们。

它的工作原理:它将大小增加一倍，直到达到限制或测试失败。然后它存储低和高之间的距离的一半，并每次减去/增加一半(失败时减去，成功时增加);磨炼成合适的值。

默认情况下，upperLimit为1GB，仅限制在开始二分查找之前以指数方式向上扫描的距离。我怀疑这种情况是否需要改变，但我总是未雨绸缪。；）

铬:

> getStorageTotalSize();
> 10485762
> 10485762/2
> 5242881
> localStorage.setItem("a", new Array(5242880).join("0")) // works
> localStorage.setItem("a", new Array(5242881).join("0")) // fails ('a' takes one spot [2 bytes])

IE11、Edge和FireFox也报告了相同的最大大小(10485762字节)。

查找可以存储在localStorage中的单个字符串的最大长度

这个代码片段将找到每个域可以存储在localStorage中的String的最大长度。

//Clear localStorage
for (var item in localStorage) delete localStorage[item];

window.result = window.result || document.getElementById('result');

result.textContent = 'Test running…';

//Start test
//Defer running so DOM can be updated with "test running" message
setTimeout(function () {

    //Variables
    var low = 0,
        high = 2e9,
        half;

    //Two billion may be a little low as a starting point, so increase if necessary
    while (canStore(high)) high *= 2;


    //Keep refining until low and high are equal
    while (low !== high) {
        half = Math.floor((high - low) / 2 + low);

        //Check if we can't scale down any further
        if (low === half || high === half) {
            console.info(low, high, half);
            //Set low to the maximum possible amount that can be stored 
            low = canStore(high) ? high : low;
            high = low;
            break;
        }


        //Check if the maximum storage is no higher than half
        if (storageMaxBetween(low, half)) {
            high = half;
            //The only other possibility is that it's higher than half but not higher than "high"
        } else {
            low = half + 1;
        }

    }

    //Show the result we found!
    result.innerHTML = 'The maximum length of a string that can be stored in localStorage is <strong>' + low + '</strong> characters.';

    //Functions
    function canStore(strLen) {
        try {
            delete localStorage.foo;
            localStorage.foo = Array(strLen + 1).join('A');
            return true;
        } catch (ex) {
            return false;
        }
    }


    function storageMaxBetween(low, high) {
        return canStore(low) && !canStore(high);
    }

}, 0);

<h1>LocalStorage single value max length test</h1>

<div id='result'>Please enable JavaScript</div>

请注意，在JavaScript中字符串的长度是有限的;如果您希望查看localStorage中可以存储的最大数据量，而不限于单个字符串，则可以使用此答案中的代码。

编辑:堆栈片段不支持localStorage，所以这里有一个到JSFiddle的链接。

结果

Chrome(45.0.2454.101): 5242878个字符 Firefox(40.0.1): 5242883个字符 Internet Explorer(11.0.9600.18036): 16386 122066 122070个字符

每次在Internet Explorer中运行都会得到不同的结果。

曾经我开发了Chrome(桌面浏览器)扩展，并为此测试了本地存储的实际最大大小。

我的结果:

Ubuntu 18.04.1 LTS (64-bit)
Chrome 71.0.3578.98 (Official Build) (64-bit)
Local Storage content size 10240 KB (10 MB)

超过10240 KB的使用返回我的错误:

Uncaught DOMException: Failed to execute 'setItem' on 'Storage':设置'notes'的值超过配额。

2020年10月23日编辑

对于一个Chrome扩展可用Chrome。存储API。如果你在manifest.js中声明了“storage”权限:

{
    "name": "My extension",
    ...
    "permissions": ["storage"],
    ...
}

你可以像这样访问它:

chrome.storage.local.QUOTA_BYTES // 5242880 (in bytes)

我编写了这段简单的代码，以字节为单位测试localStorage的大小。

https://github.com/gkucmierz/Test-of-localStorage-limits-quota

const check = bytes => {
  try {
    localStorage.clear();
    localStorage.setItem('a', '0'.repeat(bytes));
    localStorage.clear();
    return true;
  } catch(e) {
    localStorage.clear();
    return false;
  }
};

Github页面:

https://gkucmierz.github.io/Test-of-localStorage-limits-quota/

我在桌面谷歌chrome, opera, firefox, brave和移动chrome上有相同的结果，这是~10Mbytes

和一半小的结果safari约4mb

你可以在现代浏览器中使用下面的代码来实时有效地检查存储配额(总量和使用):

if ('storage' in navigator && 'estimate' in navigator.storage) {
        navigator.storage.estimate()
            .then(estimate => {
                console.log("Usage (in Bytes): ", estimate.usage,
                            ",  Total Quota (in Bytes): ", estimate.quota);
            });
}