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| __TOC__
| | #REDIRECT [[:Category:Coding Tips]] |
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| = Shortcut to document.getElementById =
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| function $(id) {
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| document.getElementById(id);
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| }
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| Example usage:
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| $("header").innerHTML = "Halloa!";
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| = XPath helper =
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| Run a particular [[XPath]] expression <code>p</code> against the context node <code>context</code> (or the document, if not provided).
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| Returns the results as an array.
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| function $x(p, context) {
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| if (!context) context = document;
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| var i, arr = [], xpr = document.evaluate(p, context, null, XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE, null);
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| for (i = 0; item = xpr.snapshotItem(i); i++) arr.push(item);
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| return arr;
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| }
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| Example usage (with [http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference:Objects:Array:forEach Array.forEach]):
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| var i, paragraphs = $x("//p");
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| paragraphs.forEach(function(paragraph) { // Loop over every paragraph
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| paragraph.innerHTML = "Halloa!";
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| });
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| = Serialize/deserialize for GM_getValue =
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| Used to store and retrieve multiple values (typically as a serialized hash) in a single [[GM_getValue]] slot.
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| function deserialize(name, def) {
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| return eval(GM_getValue(name, (def || '({})')));
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| }
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|
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| function serialize(name, val) {
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| GM_setValue(name, uneval(val));
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| }
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| Example usage:
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| var settings = {a: 1, b: 2, c: 3};
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| serialize('test', settings);
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| var _settings = deserialize('test');
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| // now "settings == _settings" should be true
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| = DOM node juggling =
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| == Remove DOM node ==
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| function remove(element) {
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| if (element)
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| element.parentNode.removeChild(element);
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| }
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| == Insert node after node ==
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| function insertAfter(newNode, node) {
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| var parent = node.parentNode;
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| return node.nextSibling ? parent.insertBefore(newNode, node.nextSibling) : parent.appendChild(newNode);
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| }
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| Example usage:
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| var link = document.getElementById("the_link");
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| var icon = document.createElement("img");
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| icon.src = "…";
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| insertAfter(icon, link);
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| = GET an URL with callback function =
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| Retrieves <code>url</code> using HTTP GET, then calls the function <code>cb</code> with the response text as its single argument.
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| function get(url, cb) {
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| GM_xmlhttpRequest({
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| method: "GET",
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| url: url,
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| onload: function(xhr) { cb(xhr.responseText); }
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| });
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| }
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| Example usage:
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| function inform(text) {
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| alert("The HTML of the page: " + text);
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| }
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| get("http://www.google.com", inform);
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