我如何估计使用JavaScript字符串的磁盘大小？ [英] How can I estimate the disk size of a string with JavaScript?

问题描述

我要尝试估计的磁盘的文本串（可以是原始文本，或者以Base64 EN codeD字符串影像/音频/等）在JavaScript中的大小。我不知道如何估算这一点。谷歌搜索我能找到的时候，唯一的事情是。长度，所以我想也许有人在计算器上可能知道...

究其原因，我需要知道的是，我有一个需要localStorage的脚本（或很想有），当用户接近他的5MB（或10MB的IE浏览器）来检查配额，促使他们增加最大规模的能力域。所以，如果一个用户点击，可以说，它会与提示数据4.5MBs

  

您正在接近你的浏览器5MB的数据上限。由... [于增加它的浏览器的说明] 的

请增加你的最大数据

解决方案

这不会是精确的，但你可以指望字符串中的字节数得到一个粗略的估计。

 函数字节（字符串）{
    VAR escaped_string = EN codeURI（字符串）;
    如果（escaped_string.indexOf（％）！=  -  1）{
        。VAR计数= escaped_string.split（％）长度 -  1;
        数=计== 0？ 1：计数;
        数=计+（escaped_string.length  - （计数* 3））;
    }
    其他{
        数= escaped_string.length;
    } 
 返回计数;
 
} 
 VAR了mystring ='助教';
警报（字节（MyString的））; 

I need to try to estimate the DISK size of a text string (which could be raw text or a Base64 encoded string for an image/audio/etc) in JavaScript. I'm not sure how to estimate this. The only thing when Googling i can find is .length so i thought maybe someone on StackOverflow might know...

The reason i need to know is i have a localStorage script that needs (or would love to have) the ability to check when a user is nearing his 5MB (or 10MB in IE) quota and prompt them to increase the max size for the domain. So, if a user hits, lets say, 4.5MBs of data it'd prompt with

You're nearing your browsers 5MB data cap. Please increase your max data by... [instructions on increasing it for the browser]

解决方案

It's not going to be exact, but you can count the number of bytes in a string to get a rough estimation.

function bytes(string) {
    var escaped_string = encodeURI(string);
    if (escaped_string.indexOf("%") != -1) {
        var count = escaped_string.split("%").length - 1;
        count = count == 0 ? 1 : count;
        count = count + (escaped_string.length - (count * 3));
    }
    else {
        count = escaped_string.length;
    }
return count;
}

var mystring = 'tâ';
alert(bytes(mystring));

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