Simple Pinger

gistfile1.coffee

# ping.txt is exactly 100 bytes

pinger = (callback, file_to_ping) ->
    ajax = start = done = null;
    ajax = if window.XMLHttpRequest then (new XMLHttpRequest()) else (new ActiveXObject('MSXML2.XMLHTTP.3.0'))
    if !ajax
        return callback?.call null, 0
    start = new Date()
    ajax.onreadystatechange = ->
        if ajax.readyState > 0
            done = new Date()
            ajax.onreadystatechange = null
            callback?.call null, done.valueOf() - start.valueOf()

    ajax.open 'HEAD', if file_to_ping then file_to_ping else 'ping.txt'
    ajax.send()


latency = 0
calls = 0
pinger (ms) ->
    latency += ms
    calls++
    pinger (ms) ->
        latency += ms
        calls++
        pinger (ms) ->
            latency += ms
            calls++
            pinger (ms) ->
                latency += ms
                calls++
                latency /= size * calls
                go(latency) # do your stuff