Custom HTML tag for GTM to strip PII from titles and URLs

pii_removal_tag.html

<script>
    //Extract Parameters into array
    function extractParams() {
        var urlParams = {},
            match,
            search = /([^&=]+)=?([^&]*)/g,
            query = window.location.search.substring(1);
        while (match = search.exec(query)) {
            urlParams[match[1]] = match[2];
        }
        return urlParams
    }
    var urlParams = extractParams()

    //Get list of parameters to retain from GTM variable
    var usefulParams = {{parameterWhitelist}}

    //Regex that defines email addresses
    var emailRegex = /(([^<>()\[\]\\.,;:\s@"%]+(\.[^<>()\[\]\\.,;:\s@"%]+)*)|(".+"))(@|%40)((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))/

    for (var key in urlParams) {
        //Check for and retain whitelisted parameters
        if (usefulParams.indexOf(key) == -1) {
            delete urlParams[key]
        }

        //Redact email address by regex
        else {
            urlParams[key] = decodeURIComponent(urlParams[key]).replace(emailRegex, "EMAIL_REDACTED")
        }
    }


    //Rewrite URL
    function rewriteURL(urlParams) {
        var keys = Object.keys(urlParams).sort();
        if (keys.length == 0) {
            return window.location.protocol + "//" + window.location.host + window.location.pathname + window.location.hash
        }
        var params = "?";
        for (var i = 0; i < keys.length; i++) {
            if (i > 0) {
                params = params.concat("&")
            }
            params = params.concat(keys[i] + "=" + urlParams[keys[i]])
        }


        return window.location.protocol + "//" + window.location.host + window.location.pathname + params + window.location.hash
    }

    var newURL = rewriteURL(urlParams);


    if (newURL !== window.location.href) {
        //History Change URL
        window.history.replaceState({}, document.title, newURL)
    }


    //Redact emails in title tags

    var newTitle = document.title.replace(emailRegex, "EMAIL_REDACTED");

    if (newTitle !== document.title) {

        document.title = newTitle
    }

    //Push to dataLayer
    dataLayer.push({
        event: "parametersRemoved"
    })
</script>