使用javascript计算textarea中的字节数 [英] Count bytes in textarea using javascript

问题描述

我需要计算使用javascript编码UTF8时textarea的字节长度。知道怎么做吗？

I need to count how long in bytes a textarea is when UTF8 encoded using javascript. Any idea how I would do this?

谢谢！

推荐答案

编辑：正如didier-l所指出的，此函数不能正确计算代理字符。

edit: as didier-l has pointed out, this function does not count surrogate characters correctly.

broofa的答案应该正确计算代理人数，请参阅 https://stackoverflow.com / a / 12206089/274483 。

broofa's answer should count surrogates properly, see https://stackoverflow.com/a/12206089/274483.

我在这里测试了两个提议版本以及一个天真的实现：

I have tested the two proposed versions here as well as a naive implementation:

 getUTF8Length: function(string) {
    var utf8length = 0;
    for (var n = 0; n < string.length; n++) {
        var c = string.charCodeAt(n);
        if (c < 128) {
            utf8length++;
        }
        else if((c > 127) && (c < 2048)) {
            utf8length = utf8length+2;
        }
        else {
            utf8length = utf8length+3;
        }
    }
    return utf8length;
 }

结果是我的版本在firefox中稍快一点，在chrome中明显加快（~30x）比这里发布的版本。

With the result that my version is slightly faster in firefox and significantly faster in chrome (~30x) than the here posted versions.

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