GTM Custom JavaScript - Hit Timestamp used for a Custom Dimension

get-hit-timestamp.js

function() {
    // Get local time as ISO string with offset at the end
    var now = new Date();
    var tzo = -now.getTimezoneOffset();
    var dif = tzo >= 0 ? '+' : '-';
    var pad = function(num) {
        var norm = Math.abs(Math.floor(num));
        return (norm < 10 ? '0' : '') + norm;
    };
    return now.getFullYear() 
        + '-' + pad(now.getMonth()+1)
        + '-' + pad(now.getDate())
        + 'T' + pad(now.getHours())
        + ':' + pad(now.getMinutes()) 
        + ':' + pad(now.getSeconds())
        + '.' + pad(now.getMilliseconds())
        + dif + pad(tzo / 60) 
        + ':' + pad(tzo % 60);
}

Code from:
https://stackoverflow.com/questions/17415579/how-to-iso-8601-format-a-date-with-timezone-offset-in-javascript/17415677#17415677