Source for "Have Temperatures Your Way!"

// ==UserScript==

// @name           Have Temperatures Your Way!

// @description    Converts Farenheit to Celsius and Celsiuc to Farenheit (displays converted number in parenthesis)

// @include        *

// ==/UserScript==

//READ THIS
//Make this C to make all temps in Celsius
//Leave at F to make all temps in fahrenheit
var convert = "C";
//Change the number below to however many decimal places you want the numbers to be..
var decimalplaces = 2;

var findF = new RegExp("([0-9]+) ?(?:(?:&deg;|&#176|Â°) ?[Ff])", "g");
var findC = new RegExp("([0-9]+) ?(?:(?:&deg;|&#176|Â°) ?[Cc])", "g");
decimalplaces = 10^decimalplaces

function FtoC(f) {
c=(f-32)*5/9;
c=Math.round(c*decimalplaces)/decimalplaces;
return (c);
}

function CtoF(c) {
f=((9/5)*c)+32;
f=Math.round(f*decimalplaces)/decimalplaces;
return (f);
}

var textnodes = document.evaluate(
    "//text()",
    document,
    null,
    XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE,
    null);

if (convert == "F") {
for (var i = 0; i < textnodes.snapshotLength; i++) {
node = textnodes.snapshotItem(i);
s = node.data;
s = s.replace(findC, CtoF(RegExp.$1)+"Â°F");
node.data = s;
}
} else {
for (var i = 0; i < textnodes.snapshotLength; i++) {
node = textnodes.snapshotItem(i);
s = node.data;
s = s.replace(findF, FtoC(RegExp.$1)+"Â°C");
node.data = s;
}
}