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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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| return document.getElementById(id);
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| }
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| Example usage:
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| $("header").innerHTML = "Halloa!";
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| = Shortcut to document.createElement with attributes =
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| Creates a new element with the given attribute list
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| function createElement(type, attributes) {
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| var element = document.createElement(type);
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| if(attributes != null) {
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| for(var i = 0; i < attributes.length; i++) {
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| element.setAttribute(attributes[i][0], attributes[i][1]);
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| }
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| }
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| return element;
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| }
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| Example usage:
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| var link = createElement('link', [['rel', 'stylesheet'], ['type', 'text/css'], ['href', basedir + 'style.css']]);
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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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| return node.parentNode.insertBefore(newNode, node.nextSibling);
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| }
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| This works because even if <i>node</i> is the last node, <i>nextSibling</i> returns <i>null</i> so <i>insertBefore</i> puts the new node at the end.
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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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|
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| get("http://www.google.com", inform);
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| = Advanced createElement for creating hierarchies of elements =
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| Creates an element with attributes as well as child elements with their own attributes and children. Arguments should be in the form of the following hash:
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| createEl({n: nodename, a: {attr1: val, attr2: val}, c: [child1, child2], evl: {type: eventlistener_type, f: eventlistener_function, bubble: bool}}, appendTo)
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| function createEl(elObj, parent) {
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| var el;
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| if (typeof elObj == 'string') {
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| el = document.createTextNode(elObj);
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| }
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| else {
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| el = document.createElement(elObj.n);
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| if (elObj.a) {
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| attributes = elObj.a;
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| for (var key in attributes) {
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| if (key.charAt(0) == '@')
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| el.setAttribute(key.substring(1), attributes[key]);
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| else
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| el[key] = attributes[key];
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| }
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| }
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| if (elObj.evl) {
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| el.addEventListener(elObj.evl.type, elObj.evl.f, elObj.evl.bubble);
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| }
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| if (elObj.c) {
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| elObj.c.forEach(function (v, i, a) { createEl(v, el); });
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| }
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| }
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| if (parent)
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| parent.appendChild(el);
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| return el;
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| }
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| Example usage:
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| createEl({n: 'ol', a: {'@class': 'some_list', '@id': 'my_list'}, c: [
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| {n: 'li', a: {textContent: 'first point'}, evl: {type: 'click', f: function() {alert('first point');}, bubble: true}},
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| {n: 'li', a: {textContent: 'second point'}},
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| {n: 'li', a: {textContent: 'third point'}}
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| ]}, document.body);
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