downlinkmax
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downlinkMax is a 0.26KB Network Information API polyfill for navigator.connection.downlinkMax written in both CoffeeScript and JavaScript with AMD support.
50 lines (43 loc) • 1.72 kB
JavaScript
/**
* @file downlinkMax is 0.26KB Network Information API downlinkMax polyfill micro-library.
* @author Daniel Lamb <dlamb.open.source@gmail.com>
*/
function downlinkmax() {
var limitless = Infinity,
nav = navigator,
speed,
// deal with vendor prefixing and fallback if not supported
connection = nav.connection || nav.mozConnection || nav.webkitConnection || {
// API not supported
downlinkMax: limitless
};
// check that the API doesn't already support downlinkMax
if (!('downlinkMax' in connection)) {
// assume NOT W3C Editor's Draft 09 October 2014
// check if API supports bandwidth
if ('bandwidth' in connection) {
// assume W3C Working Draft 29 November 2012
// standardize connection.bandwidth value by converting megabytes per second (MB/s) to megabits per second (Mbit/s)
connection.downlinkMax = connection.bandwidth * 8;
} else {
// assume W3C Working Draft 07 June 2011
// convert connection.type value to approximate downlink values
// speed estimate is based on the median downlink value for common devices in megabits per second (Mbit/s)
switch (connection.type) {
case 'none': speed = 0; break;
case '2g': speed = 0.134; break;
case 'bluetooth':
case 'cellular': speed = 2; break;
case '3g': speed = 8.95; break;
case '4g': speed = 100; break;
case 'ethernet': speed = 550; break;
case 'wifi': speed = 600; break;
// other, unknown etc.
default: speed = limitless; break;
}
connection.downlinkMax = speed;
}
}
// return the maximum downlink speed
return connection.downlinkMax;
}