如何在JavaScript中计算Content-Length

function Likesdislikes () {

    $.ajax({
        url: 'http://gdata.youtube.com/Feeds/api/videos/keDZXXDxK1c/ratings',
        type:"POST",
        data: '<?xml version="1.0" encoding="UTF-8"?>
            <entry xmlns="http://www.w3.org/2005/Atom"
                   xmlns:yt="http://gdata.youtube.com/schemas/2007">
                <yt:rating value="like"/>
            </entry>',
        headers: {
            "Content-Type":"application/atom+xml",
            "Content-Length":,
            "Authorization":"Bearer ya29.AHES6ZQ59RrQgujZmIjssBdYlwwLVrpCodnirdLROi7-g7U",
            "X-GData-Key":"key=AIzaSyAPrtP2Tq4m5WVInCvcwptVAKPhQ4SQNZA",
            "GData-Version":"2"
        },
        // Content-Type:"application/atom+xml",
        error: function() { alert("No data found."); },
        // contentType: "text/xml",
        success: function (response) {
            alert('response:' + response);
        }
   });

}

如何在上面的代码中计算Content-Length？

解决方法:

如specs所述

The Content-Length entity-header field indicates the size of the
entity-body, in decimal number of OCTETs

请看这个问题String length in bytes in JavaScript.

基本上,如果您的数据只包含ASCII字符,一切都应该很容易

function Likesdislikes () {

    var data = '<?xml version="1.0" encoding="UTF-8"?>
    <entry xmlns="http://www.w3.org/2005/Atom"
           xmlns:yt="http://gdata.youtube.com/schemas/2007">
        <yt:rating value="like"/>
    </entry>';

    $.ajax({
        url: 'http://gdata.youtube.com/Feeds/api/videos/keDZXXDxK1c/ratings',
        type:"POST",
        data: data,
        headers: {
            "Content-Type":"application/atom+xml",
            "Content-Length": data.length,
            "Authorization":"Bearer ya29.AHES6ZQ59RrQgujZmIjssBdYlwwLVrpCodnirdLROi7-g7U",
            "X-GData-Key":"key=AIzaSyAPrtP2Tq4m5WVInCvcwptVAKPhQ4SQNZA",
            "GData-Version":"2"
        },
        // Content-Type:"application/atom+xml",
        error: function() { alert("No data found."); },
        // contentType: "text/xml",
        success: function (response) {
            alert('response:' + response);
        }
    });
}