Automatically detect page language and add lang attribute to html tag, helps browser display proper fonts and typography
// ==UserScript==
// @name Auto lang attr
// @name:zh-CN 自动 lang 属性
// @namespace auto.lang.attr
// @version 1.0
// @description Automatically detect page language and add lang attribute to html tag, helps browser display proper fonts and typography
// @description:zh-CN 自动监测页面语言并给 html 元素添加 lang 标签，有助于浏览器正确显示字体和排版
// @author o
// @match *://*/*
// @grant GM_getValue
// @grant GM_setValue
// @grant GM_registerMenuCommand
// @grant GM_unregisterMenuCommand
// @license MIT
// ==/UserScript==
(function() {
'use strict';
// Whitelist management
const WHITELIST_KEY = 'lang_attr_whitelist';
let whitelist = GM_getValue(WHITELIST_KEY, []);
let menuCommandId = null;
// Get current domain
const currentDomain = window.location.hostname;
// Check if current domain is in whitelist
const isWhitelisted = whitelist.includes(currentDomain);
// Register menu command
function registerMenuCommand() {
if (menuCommandId !== null) {
GM_unregisterMenuCommand(menuCommandId);
}
const commandText = isWhitelisted ?
`Enable for ${currentDomain}` :
`Disable for ${currentDomain}`;
menuCommandId = GM_registerMenuCommand(commandText, toggleWhitelist);
}
// Toggle domain in whitelist
function toggleWhitelist() {
if (isWhitelisted) {
// Remove from whitelist
whitelist = whitelist.filter(domain => domain !== currentDomain);
} else {
// Add to whitelist
whitelist.push(currentDomain);
}
GM_setValue(WHITELIST_KEY, whitelist);
window.location.reload(); // Reload to apply changes
}
// Register the menu command
registerMenuCommand();
// If whitelisted and enabled, skip processing
if (isWhitelisted) {
return;
}
// Check if html tag already has lang attribute
const htmlElement = document.documentElement;
if (htmlElement.hasAttribute('lang')) {
return; // Exit if lang attribute already exists
}
// Function to detect language from text content
function detectLanguage(text) {
// Common language patterns (simplified detection)
const languagePatterns = {
'en': /\b(the|and|to|of|a|in|that|is|for|it)\b/gi,
'es': /\b(el|la|los|las|de|que|y|en|a|un)\b/gi,
'fr': /\b(le|la|les|de|et|à|en|des|un|une)\b/gi,
'de': /\b(der|die|das|und|in|zu|den|von|mit|sich)\b/gi,
'pt': /\b(o|a|os|as|de|e|em|um|uma|que)\b/gi,
'it': /\b(il|lo|la|i|gli|le|di|e|a|in)\b/gi,
'ru': /\b(и|в|не|на|я|что|с|а|он|к)\b/gi,
'zh': /[\u4e00-\u9fff]/g, // Chinese characters
'ja': /[\u3040-\u309f\u30a0-\u30ff\u4e00-\u9fff]/g, // Hiragana, Katakana, Kanji
'ko': /[\uac00-\ud7af\u1100-\u11ff]/g, // Hangul syllables and jamo
'ar': /[\u0600-\u06FF]/g, // Arabic script
'hi': /[\u0900-\u097F]/g // Devanagari script (Hindi)
};
let maxCount = 0;
let detectedLang = 'en'; // Default to English
// Count occurrences of language patterns
for (const [lang, pattern] of Object.entries(languagePatterns)) {
const matches = text.match(pattern);
const count = matches ? matches.length : 0;
if (count > maxCount) {
maxCount = count;
detectedLang = lang;
}
}
// If no strong pattern matches found, use more sophisticated detection
if (maxCount < 3) {
// Try to detect from meta tags
const metaLang = document.querySelector('meta[http-equiv="content-language"], meta[name="language"]');
if (metaLang && metaLang.content) {
return metaLang.content.split('-')[0]; // Get primary language code
}
// Try to detect from charset or other hints
const charset = document.characterSet || document.charset;
if (charset && charset.toLowerCase().includes('utf')) {
// For UTF pages, we might need more context
// Check for specific language indicators in the page
const bodyText = document.body.textContent.toLowerCase();
if (bodyText.includes('的') || bodyText.includes('是')) return 'zh';
if (bodyText.includes('は') || bodyText.includes('です')) return 'ja';
if (bodyText.includes('입니다') || bodyScript.includes('는')) return 'ko';
}
}
return detectedLang;
}
// Get text content from the page (limit to first 5000 chars for performance)
const pageText = document.body.textContent.substring(0, 5000);
if (pageText.trim().length > 100) { // Only detect if there's sufficient text
const detectedLanguage = detectLanguage(pageText.toLowerCase());
// Set the lang attribute
htmlElement.setAttribute('lang', detectedLanguage);
console.log(`Language detected: ${detectedLanguage}, lang attribute added to html tag`);
}
})();