Google reCAPTCHA V2. Change language in real time

script.js

// Enum for language codes
var languageListsGoogleCaptchaEnum = {
    Arabic: 'ar',
    Afrikaans: 'af',
    Amharic: 'am',
    Armenian: 'hy',
    Azerbaijani: 'az',
    Basque: 'eu',
    Bengali: 'bn',
    Bulgarian: 'bg',
    Catalan: 'ca',
    Chinese_HongKong: 'zh-HK',
    Chinese_Simplified: 'zh-CN',
    Chinese_Traditional: 'zh-TW',
    Croatian: 'hr',
    Czech: 'cs',
    Danish: 'da',
    Dutch: 'nl',
    English_UK: 'en-GB',
    English_US: 'en',
    Estonian: 'et',
    Filipino: 'fil',
    Finnish: 'fi',
    French: 'fr',
    French_Canadian: 'fr-CA',
    Galician: 'gl',
    Georgian: 'ka',
    German: 'de',
    German_Austria: 'de-AT',
    German_Switzerland: 'de-CH',
    Greek: 'el',
    Gujarati: 'gu',
    Hebrew: 'iw',
    Hindi: 'hi',
    Hungarain: 'hu',
    Icelandic: 'is',
    Indonesian: 'id',
    Italian: 'it',
    Japanese: 'ja',
    Kannada: 'kn',
    Korean: 'ko',
    Laothian: 'lo',
    Latvian: 'lv',
    Lithuanian: 'lt',
    Malay: 'ms',
    Malayalam: 'ml',
    Marathi: 'mr',
    Mongolian: 'mn',
    Norwegian: 'no',
    Persian: 'fa',
    Polish: 'pl',
    Portuguese: 'pt',
    Portuguese_Brazil: 'pt-BR',
    Portuguese_Portugal: 'pt-PT',
    Romanian: 'ro',
    Russian: 'ru',
    Serbian: 'sr',
    Sinhalese: 'si',
    Slovak: 'sk',
    Slovenian: 'sl',
    Spanish: 'es',
    Spanish_LatinAmerica: 'es-419',
    Swahili: 'sw',
    Swedish: 'sv',
    Tamil: 'ta',
    Telugu: 'te',
    Thai: 'th',
    Turkish: 'tr',
    Ukrainian: 'uk',
    Urdu: 'ur',
    Vietnamese: 'vi',
    Zulu: 'zu',
};

// Update language captcha 
function updateGoogleCaptchaLanguage(selectedLanguage) {
    var iframeGoogleCaptcha = (document.getElementById('recaptcha')).getElementsByTagName('iframe')[0];
    var language = iframeGoogleCaptcha.src.match(/hl=(.*?)&/).pop();
    iframeGoogleCaptcha.src = iframeGoogleCaptcha.src.replace(/hl=(.*?)&/, 'hl=' + selectedLanguage + '&');
}

You need simply call updateGoogleCaptchaLanguage(selectedLanguage) with selected language

recaptcha in the code above is the id of the div with initialized google recaptcha