Code snippets

XPath helper

function $x(p, context) {
  if (!context) context = document;
  var i, arr = [], xpr = document.evaluate(p, context, null, XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE, null);
  for (i = 0; item = xpr.snapshotItem(i); i++) arr.push(item);
  return arr;
}

Run a particular xpath expression p against the context node context (or the document, if not provided). Return the results as an array.

Serialize/deserialize

Used to store and retrieve multiple values (typically as a serialized hash) in a single GM_getValue slot.

function deserialize(name, def) {
  return eval(GM_getValue(name, (def ? def : '({})')));
}

function serialize(name, val) {
  GM_setValue(name, uneval(val));
}

Example usage:

var settings = {a: 1, b: 2, c: 3};
serialize('test', settings);
var _settings = deserialize('test');
// now "settings == _settings" should be true