The High Resolution Time standard defines a Performance interface that supports client-side latency measurements within applications. The Performance interfaces are considered high resolution because they are accurate to a thousandth of a millisecond (subject to hardware or software constraints). The interfaces support a number of use cases including calculating frame-rates (potentially important in animations) and benchmarking (such as the time to load a resource).
A WebSocket server is a TCP application listening on any port of a server that follows a specific protocol, simple as that. The task of creating a custom server tends to scare people; however, it can be easy to implement a simple WebSocket server on your platform of choice.
Window.outerWidth gets the width of the outside of the browser window. It represents the width of the whole browser window including sidebar (if expanded), window chrome and window resizing borders/handles.
The XMLHttpRequest.send() method sends the request. If the request is asynchronous (which is the default), this method returns as soon as the request is sent. If the request is synchronous, this method doesn't return until the response has arrived. send() accepts an optional argument for the request body. If the request method is GET or HEAD, the argument is ignored and request body is set to null.
In HTML5, some HTML elements which provide support for CORS, such as <img> or <video>, have a crossorigin attribute (crossOrigin property), which lets you configure the CORS requests for the element's fetched data. These attributes are enumerated, and have the following possible values: