'use strict';
const CHARTSET_RE = /(?:charset|encoding)\s*=\s*['"]? *([\w\-]+)/i;
module.exports = charset;
/**
* guest data charset from req.headers, xml, html content-type meta tag
* headers:
* 'content-type': 'text/html;charset=gbk'
* meta tag:
* <meta http-equiv="Content-Type" content="text/html; charset=xxxx"/>
* xml file:
* <?xml version="1.0" encoding="UTF-8"?>
*
* @param {Object} obj `Content-Type` String, or `res.headers`, or `res` Object
* @param {Buffer} [data] content buffer
* @param {Number} [peekSize] max content peek size, default is 512
* @return {String} charset, lower case, e.g.: utf8, gbk, gb2312, ....
* If can\'t guest, return null
* @api public
*/
function charset(obj, data, peekSize) {
let matchs = null;
let end = 0;
if (data) {
peekSize = peekSize || 512;
// https://github.com/node-modules/charset/issues/4
end = data.length > peekSize ? peekSize : data.length;
}
// charset('text/html;charset=gbk')
let contentType = obj;
if (contentType && typeof contentType !== 'string') {
// charset(res.headers)
let headers = obj;
if (obj.headers) {
// charset(res)
headers = obj.headers;
}
contentType = headers['content-type'] || headers['Content-Type'];
}
if (contentType) {
// guest from obj first
matchs = CHARTSET_RE.exec(contentType);
}
if (!matchs && end > 0) {
// guest from content body (html/xml) header
contentType = data.slice(0, end).toString();
matchs = CHARTSET_RE.exec(contentType);
}
let cs = null;
if (matchs) {
cs = matchs[1].toLowerCase();
if (cs === 'utf-8') {
cs = 'utf8';
}
}
return cs;
}
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