js判断网页编码

function getMetaCharset() {
    var meta = document.getElementsByTagName('meta');
    for (var i = 0; i < meta.length; i++) {
        if (meta[i].getAttribute('charset')) {
            return meta[i].getAttribute('charset');
        }
        if (meta[i].getAttribute('http-equiv') === 'Content-Type' && meta[i].getAttribute('content')) {
            var content = meta[i].getAttribute('content');
            var charsetIndex = content.indexOf('charset=');
            if (charsetIndex !== -1) {
                return content.substring(charsetIndex + 8);
            }
        }
    }
    return null;
}

console.log(getMetaCharset());

console.log(document.characterSet);

fetch(window.location.href)
    .then(response => {
        console.log(response.headers.get('Content-Type'));
    })
    .catch(error => console.error('Error:', error));