hostsRequestedCounts

var har = require('./har.json');
var entries = har['log']['entries'];
var hosts = {};

for (var i = 0; i < entries.length; i++) {
    var entry = entries[i];
    var headers = entry['request']['headers'];
    for (var j = 0; j < headers.length; j++) {
        var header = headers[j];
        if (header['name'] == 'Host') {
            if (hosts[header['value']]) {
                hosts[header['value']] += 1;
            } else {
                hosts[header['value']] = 1
            }
        }
    }
}

console.log(hosts);