The W3C XMLHttpRequest specification adds HTML parsing support to XMLHttpRequest, which originally supported only XML parsing. This feature allows Web apps to obtain an HTML resource as a parsed DOM using XMLHttpRequest.
The XMLHttpRequest.responseXML property returns a Document containing the response to the request, or null if the request was unsuccessful, has not yet been sent, or cannot be parsed as XML or HTML. The response is parsed as if it were a text/xml stream. When the responseType is set to "document" and the request has been made asynchronously, the response is parsed as a text/html stream. responseXML is null for data: URLs.
The XMLHttpRequest.status property returns the numerical status code of the response of the XMLHttpRequest. status will be an unsigned short. Before the request is complete, the value of status will be 0. It is worth noting that browsers report a status of 0 in case of XMLHttpRequest errors too.
The XMLHttpRequest.statusText property returns a DOMString containing the response's status message as returned by the HTTP server. Unlike XMLHTTPRequest.status which indicates a numerical status code, this property contains the text of the response status, such as "OK" or "Not Found". If the request's readyState is in UNSENT or OPENED state, the value of statusText will be an empty string.
The fftSize property of the AnalyserNode interface is an unsigned long value representing the size of the FFT (Fast Fourier Transform) to be used to determine the frequency domain.
The frequencyBinCount property of the AnalyserNode interface is an unsigned long value half that of the FFT size. This generally equates to the number of data values you will have to play with for the visualization.
The maxDecibels property of the AnalyserNode interface Is a double value representing the maximum power value in the scaling range for the FFT analysis data, for conversion to unsigned byte/float values — basically, this specifies the maximum value for the range of results when using getFloatFrequencyData() or getByteFrequencyData().
The minDecibels property of the AnalyserNode interface Is a double value representing the minimum power value in the scaling range for the FFT analysis data, for conversion to unsigned byte/float values — basically, this specifies the minimum value for the range of results when using getFloatFrequencyData() or getByteFrequencyData().
The smoothingTimeConstant property of the AnalyserNode interface is a double value representing the averaging constant with the last analysis frame. It's basically an average
between the current buffer and the last buffer the AnalyserNode processed, and results in a much smoother set of value changes over time.