js获取input中文长度

function getByteLength(str) {
    let byteLength = 0;
    for (let i = 0; i < str.length; i++) {
        const charCode = str.charCodeAt(i);
        if (charCode <= 0x007F) {
            // 单字节字符 (0x00 - 0x7F)
            byteLength += 1;
        } else if (charCode <= 0x07FF) {
            // 双字节字符 (0x80 - 0x7FF)
            byteLength += 2;
        } else if (charCode <= 0xFFFF) {
            // 三字节字符 (0x800 - 0xFFFF)
            byteLength += 3;
        } else {
            // 四字节字符 (0x10000 - 0x10FFFF)
            byteLength += 4;
        }
    }
    return byteLength;
}

// 使用示例
const inputElement = document.querySelector('input');
inputElement.addEventListener('input', function() {
    const chineseText = this.value;
    const lengthInBytes = getByteLength(chineseText);
    console.log(`中文字符串的字节长度是: ${lengthInBytes}`);
});