Umsetzung des Google Consent Mode V2

window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}

let GOOGLE_CONSENT_V2_DEFAULT_STATE = 'denied';
let GOOGLE_CONSENT_V2_STORAGE_KEY = 'consentMode';

let GOOGLE_CONSENT_V2_FIELDS = [
    'ad_storage', // adwords
    'ad_user_data', // adwords
    'ad_personalization', // adwords
    'analytics_storage', // analytics
    'personalization_storage', // necessary
    'functionality_storage', // necessary
    'security_storage', // necessary
];

// sample for custom event handlers
let GOOGLE_CONSENT_V2_FIELDS_EVENTS = {
    'analytics_storage': {
        'on_granted': function() {},
        'on_denied': function() {}
    }
}

// get current settings
let consentStorage= localStorage.getItem(GOOGLE_CONSENT_V2_STORAGE_KEY);

if(consentStorage === null) {
    // init of consent settings
    let defaultSettings = array_combine(GOOGLE_CONSENT_V2_FIELDS, array_fill(0, GOOGLE_CONSENT_V2_FIELDS.length, GOOGLE_CONSENT_V2_DEFAULT_STATE));

    if(defaultSettings !== false) {
        gtag('consent', 'default', defaultSettings);
        localStorage.setItem(GOOGLE_CONSENT_V2_STORAGE_KEY, JSON.stringify(defaultSettings));
    }
} else {
    // check if array is consistent (if new entries appear in the future)
    let storedSettings = JSON.parse(consentStorage);

    if(Object.keys(storedSettings).length !== GOOGLE_CONSENT_V2_FIELDS.length) {
        GOOGLE_CONSENT_V2_FIELDS.forEach((field) => {
            if (typeof storedSettings[field] == "undefined") {
                storedSettings[field] = GOOGLE_CONSENT_V2_DEFAULT_STATE;
            }
        });

        gtag('consent', 'default', storedSettings);
        localStorage.setItem(GOOGLE_CONSENT_V2_STORAGE_KEY, JSON.stringify(storedSettings));
    }
}

if(localStorage.getItem('userId') != null) {
    window.dataLayer.push({'user_id': localStorage.getItem('userId')});
}

function setConsent(consent) {
    let consentSettings = JSON.parse(localStorage.getItem(GOOGLE_CONSENT_V2_STORAGE_KEY));

    for (const [key, value] of Object.entries(consentSettings)) {
        if (typeof consent[key] !== "undefined") {
            if(typeof(GOOGLE_CONSENT_V2_FIELDS_EVENTS[key]) != 'undefined') {
                if(consent[key] === true && consentSettings[key] === 'denied') {
                    GOOGLE_CONSENT_V2_FIELDS_EVENTS[key]['on_granted']();
                } else if (consent[key] === false && consentSettings[key] === 'granted') {
                    GOOGLE_CONSENT_V2_FIELDS_EVENTS[key]['on_denied']();
                }
            }

            consentSettings[key] = (consent[key] === true ? 'granted' : 'denied');
        }
    }

    gtag('consent', 'update', consentSettings);
    localStorage.setItem(GOOGLE_CONSENT_V2_STORAGE_KEY, JSON.stringify(consentSettings));
}

/**
 * helper to bring in PHP's array_combine function
 * @param keys
 * @param values
 */
function array_combine(keys, values) {
    const newArray = {}
    let i = 0

    if (
        typeof keys !== 'object' ||
        typeof values !== 'object' ||
        typeof keys.length !== 'number' ||
        typeof values.length !== 'number' ||
        !keys.length ||
        !values.length ||
        keys.length !== values.length
    ) {
        return false;
    }

    for (i = 0; i < keys.length; i++) {
        newArray[keys[i]] = values[i]
    }

    return newArray;
}

/**
 * helper to bring in PHP's array_fill function
 * @param startIndex
 * @param num
 * @param mixedVal
 * @return 
 */
function array_fill(startIndex, num, mixedVal) {
    let key;
    const tmpArr= [];

    if (!isNaN(startIndex) && !isNaN(num)) {
        for (key = 0; key < num; key++) {
          tmpArr[(key + startIndex)] = mixedVal
        }
    }

    return tmpArr;
}

<script> setConsent({
    ad_storage: true,
    ad_user_data: true,
    ad_personalization: true
}); </script>

<script>setConsent({
    functionality_storage: true,
    personalization_storage: true,
    security_storage: true
});</script>