Laurent Dami > Alien-GvaScript > GvaScript.protoExtensions


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GvaScript.protoExtensions - Extensions to prototype.js


  Element.hasAnyClass(elem, ["class1", "class2", ...]);  
  Element.getElementsByClassNames(elem, ["class1", "class2", ...]);  

  var stop_condition = function(elem) { return elem.tagName == "SPAN"};
  Element.navigateDom(elem, "nextSibling", ["class1", "class2", ...],

  this.options = Class.checkOptions(defaultOptions, receivedOptions);

  Element.register(elem, '', 'mouseover', function(e) {
  Element.unregister(elem, '', 'mouseover');, key, value);
  Element.retrieve(elem, key, default);


Some extensions to the basic abstractions supplied by prototype.js.


Events delegation

  Will be a part of prototype's core distribution starting version 1.7
  as discussed here 


  Prototype.getJSON(url, callback)

based on: getJSON function by Juriy Zaytsev

A method to temporarily load JSON data (ideally hosted on a different domain and accessible via JSONP service) and send it over to callback method when ready.

Hash utilities


  var tree = Hash.expand(flat_hash);

Transforms a flat structure of key-value pairs into a nested tree structure, by splitting keys on dots. The idea and algorithm come from "expand_hash" in CGI::Expand.

  Hash.expand({a: '...', b.0.x: '...', b.0.y: '...', b.1.x: '...', b.1.y: '...'}) =>
  {a: '...', b: [{x: '...', y: '...'}, {x: '...', y: '...'}]}


The exact opposite of Hash.expand

Transforms a nested tree structure into a flat hash of key-value pairs where nested keys are joined by a dot.

String extensions


Strips any trailing line breaks (\r\n) from a String.

Element extensions


only applied to ['SPAN', 'DIV', 'INPUT', 'BUTTON', 'TEXTAREA', 'A'] elements.

used to set a classname to the element for a brief moment of time.

  Element.flash(elem, {duration: I<time_mes>, classname: I<classname_to_set>});


  if (Element.hasAnyClass(elem, ["class1", "class2", ...]) {...}  

  if (Element.hasAnyClass(elem, "class1") {...}  

Returns true if the supplied element has any of the given classes. For convenience, also accepts a single string instead of an array when testing for a single class.


  var subElements 
     = Element.getElementsByClassNames(rootElement, ["class1", "class2", ...]);

Returns an array of children of rootElement that have any of the given class names.


  var wantedClasses = ["class1", "class2", ...];
  // which direction to navigate (could be "parentNode", etc.)
  var direction     = "nextSibling"; 

  // some criteria for stopping navigation (can be anything, here a stupid
  // example)
  var stopCondition = function(elem) {return elem.innerHTML.length > 10}

  var nextElement
    = Element.navigateDom(startElement, direction, wantedClasses,

Returns an extended (prototype's Element.extend()) copy of HTMLElement.

Walks through the DOM in the given direction, until finding an element that has one of the given classnames, or finding a stop condition (in which case null is returned).


  Element.autoScroll(elem, percentage) 

Makes sure that elem is visible in the central area of its offset parent; if not, the parent is scrolled. percentage is the ratio between the parent height and the margin at which scrolling must occur, i.e. if percentage = 20 (the default), then scrolling occurs if the element is in the higher than the top 20% or lower than the bottom 20% of the viewport.



Returns a string representation of the DOM element, including tags and attributes. Implemented through the native outerHTML property, if present; otherwise constructs a string from tag name, attributes and innerHTML property.

Form.Element extensions


Form.Element.setValue method is wrapped to fire a 'value:change' custom event with oldvalue and newvalue properties set in the event.memo

Event extensions


  Event.detailedStop(event, toStop);

Browser-independent method to control fine details of event stopping within event handlers. The toStop argument is an object which may contain the following properties:


if true, the event will not be passed to further handlers up the bubbling hierarchy.


if true, the default behaviour of the browser for that event will be cancelled


Just a convenience object, having both properties above set to true. So

  Event.detailedStop(event, Event.stopAll);

is equivalent to calling prototype's Event.stop(event).

Class extensions


  this.options = Class.checkOptions(defaultOptions, ctorOptions)

Utility for constructor methods. The first argument is an object containing a collection of default options (keys and values). The second argument is a similar object, containing options given to the constructor.

If one of the keys in ctorOptions has no corresponding key in defaultOptions, an error is generated (because the constructor does not expect such a key). Otherwise, the concatenation of both objects is returned (i.e. values in ctorOptions take precedence over values in defaultOptions).


  ASSERT (cond, msg);

Checks if cond is true, and if not, generates an error with message msg.



Returns value of CSS_PREFIX global variable if found. If not, default to 'gva'.

This value is used to prefix css classnames of html elements that are derived in some GvaScript classes.

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