localStorage值的最大大小是多少？

Question

由于localStorage(当前)仅支持字符串作为值,并且为了做到这一点,对象需要在存储之前进行字符串化(存储为JSON字符串),是否存在关于值的长度的定义限制.

有谁知道是否有适用于所有浏览器的定义？

Answer 1

引自Wikipedia关于Web存储的文章:

Web存储可以简单地视为对cookie的改进,提供更大的存储容量(Google Chrome中的每个源10 MB(https://plus.google.com/u/0/+FrancoisBeaufort/posts/S5Q9HqDB8bh),Mozilla Firefox和Opera; Internet Explorer中每个存储区域10 MB)和更好的编程接口.

并引用John Resig的文章 [2007年1月发布]:

储存空间

暗示使用DOM存储,您拥有的存储空间远远超过对Cookie施加的典型用户代理限制.但是,提供的数量未在规范中定义,也未由用户代理有意义地广播.

如果查看Mozilla源代码,我们可以看到5120KB是整个域的默认存储大小.与典型的2KB cookie相比,这为您提供了更多的工作空间.

但是,此存储区域的大小可以由用户自定义(因此不保证5MB存储区域,也不暗示)和用户代理(例如,Opera可能只提供3MB - 但只有时间会告诉您. )

Answer 2

实际上Opera没有5MB的限制.它提供了增加限制,因为应用程序需要更多.用户甚至可以为域选择"无限存储".

您可以自己轻松测试localStorage限制/配额.

Answer 3

这是一个直接找到限制的脚本:

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);            
    }
}

这是gist,JSFiddle和博客文章.

该脚本将测试设置越来越大的文本字符串,直到浏览器抛出异常.此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.

Answer 4

移动浏览器:

Browser    | Chrome    | Android Browser    | Firefox     | iOS Safari
Version    | 40        | 4.3                | 34          | 6-8
Available  | 10MB      | 2MB                | 10MB        | 5MB

桌面浏览器:

Browser    | Chrome   | Opera    | Firefox    | Safari      | IE
Version    | 40       | 27       | 34         | 6-8         | 9-11
Available  | 10MB     | 10MB     | 10MB       | 5MB         | 10MB

Answer 5

找到可以存储的单个字符串的最大长度 localStorage

此代码段将查找可以存储在localStorage每个域中的字符串的最大长度.

//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,字符串的长度在JavaScript中是有限的; 如果要查看localStorage不限于单个字符串时可以存储的最大数据量,可以使用此答案中的代码.

编辑: Stack Snippets不支持localStorage,所以这里是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

我在Internet Explorer的每次运行中得到不同的结果.

Answer 6

不要假设5MB可用 - localStorage容量因浏览器而异,2.5MB,5MB,无限制是最常见的值.资料来源:http://dev-test.nemikor.com/web-storage/support-test/

Answer 7

您不希望将大对象字符串化为单个localStorage条目.这将是非常低效的 - 每次细微的细节变化时,整个事情都必须被解析和重新编码.此外,JSON无法处理对象结构中的多个交叉引用并消除了许多细节,例如构造函数,数组的非数字属性,稀疏条目中的内容等.

相反,您可以使用http://rhaboo.org.它使用大量localStorage条目存储大型对象,因此您可以快速进行小的更改.恢复的对象是保存的对象的更准确的副本,API非常简单.例如:

var store = Rhaboo.persistent('Some name');
store.write('count', store.count ? store.count+1 : 1);
store.write('somethingfancy', {
  one: ['man', 'went'],
  2: 'mow',
  went: [  2, { mow: ['a', 'meadow' ] }, {}  ]
});
store.somethingfancy.went[1].mow.write(1, 'lawn');

顺便说一下,我写了.

Answer 8

我写了这个简单的代码，以字节为单位测试 localStorage 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 chrome、opera、firefox、brave 和移动 chrome 上有相同的结果，大约 5Mbytes

小一半的结果是 safari ~2Mbytes

Answer 9

我真的很喜欢cdmckay的答案,但是实时检查大小并不是很好看:它太慢了(对我来说是2秒).这是改进版本,它更快,更精确,也可以选择错误的大小(默认情况下250,000,误差越小 - 计算时间越长):

function getLocalStorageMaxSize(error) {
  if (localStorage) {
    var max = 10 * 1024 * 1024,
        i = 64,
        string1024 = '',
        string = '',
        // generate a random key
        testKey = 'size-test-' + Math.random().toString(),
        minimalFound = 0,
        error = error || 25e4;

    // fill a string with 1024 symbols / bytes    
    while (i--) string1024 += 1e16;

    i = max / 1024;

    // fill a string with 'max' amount of symbols / bytes    
    while (i--) string += string1024;

    i = max;

    // binary search implementation
    while (i > 1) {
      try {
        localStorage.setItem(testKey, string.substr(0, i));
        localStorage.removeItem(testKey);

        if (minimalFound < i - error) {
          minimalFound = i;
          i = i * 1.5;
        }
        else break;
      } catch (e) {
        localStorage.removeItem(testKey);
        i = minimalFound + (i - minimalFound) / 2;
      }
    }

    return minimalFound;
  }
}

去测试:

console.log(getLocalStorageMaxSize()); // takes .3s
console.log(getLocalStorageMaxSize(.1)); // takes 2s, but way more exact

这对标准错误的速度要快得多; 在必要时它也可以更精确.

Answer 10

我已经将二进制测试压缩到我使用的此函数中：

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，然后将其还原。

工作原理：将大小增加一倍，直到达到限制或测试失败。然后，它存储高低点之间的距离的一半，并且每次减去/相加一半的一半（减去失败并增加成功）；磨成适当的价值。

upperLimit默认情况下为1GB，并且仅限制在开始二进制搜索之前向上扫描的指数范围。我怀疑这甚至需要更改，但是我一直在思考。;）

在Chrome上：

> 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也报告相同的最大大小（10485762字节）。

Answer 11

我正在执行以下操作：

getLocalStorageSizeLimit = function () {

    var maxLength = Math.pow(2,24);
    var preLength = 0;
    var hugeString = "0";
    var testString;
    var keyName = "testingLengthKey";

    //2^24 = 16777216 should be enough to all browsers
    testString = (new Array(Math.pow(2, 24))).join("X");

    while (maxLength !== preLength) {
        try  {
            localStorage.setItem(keyName, testString);

            preLength = testString.length;
            maxLength = Math.ceil(preLength + ((hugeString.length - preLength) / 2));

            testString = hugeString.substr(0, maxLength);
        } catch (e) {
            hugeString = testString;

            maxLength = Math.floor(testString.length - (testString.length - preLength) / 2);
            testString = hugeString.substr(0, maxLength);
        }
    }

    localStorage.removeItem(keyName);

    maxLength = JSON.stringify(this.storageObject).length + maxLength + keyName.length - 2;

    return maxLength;
};

Answer 12

您可以在现代浏览器中使用以下代码来实时有效地检查存储配额(总计和已使用):

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);
            });
}