Identify if a Marketing Channel Clickthrough was performed

isChannelClickthrough.js

function isChannelClickthrough(channel_parameter, referrer) {
    // Tealium-specific variable to identify first hit of session.
    var session_hit_number = b.tealium_session_event_number;
    // If channel_parameter is present, paid channel click-through occured
    if (channel_parameter && channel_parameter !== '')
        return true;
    else if (referrer && referrer !== '') {
        if (identifyChannels(NATURAL_SEARCH, DOMAINS_NATURAL_SEARCH, referrer) 
            || identifyChannels(NATURAL_SOCIAL, DOMAINS_NATURAL_SOCIAL, referrer) 
            || identifyChannels(REFERRING_DOMAIN, DOMAINS_REFERRING, referrer))
            return true;
    } else if (session_hit_number === 1 && referrer === '')
        return true;
    else
        return false;
}