ElementTraversal.js: W3C勧告の ElementTraversal を実装するJavaScriptライブラリ

ElementTraversal.js

/**
 * ElementTraversal.js
 *
 * @version 1.0
 * @author think49
 */


/**
 * Interface Node
 *   http://www.w3.org/TR/DOM-Level-3-Core/core.html#ID-1950641247
 */
var Node = typeof Node === 'function' || typeof Node === 'object' ? Node : (function () {
      function Node () { ; }

      // NodeType
      Node.ELEMENT_NODE = 1;
      Node.ATTRIBUTE_NODE = 2;
      Node.TEXT_NODE = 3;
      Node.CDATA_SECTION_NODE = 4;
      Node.ENTITY_REFERENCE_NODE = 5;
      Node.ENTITY_NODE = 6;
      Node.PROCESSING_INSTRUCTION_NODE = 7;
      Node.COMMENT_NODE = 8;
      Node.DOCUMENT_NODE = 9;
      Node.DOCUMENT_TYPE_NODE = 10;
      Node.DOCUMENT_FRAGMENT_NODE = 11;
      Node.NOTATION_NODE = 12;

      return Node;
    })();

/**
 * Interface ElementTraversal
 *   http://www.w3.org/TR/ElementTraversal/
 *   http://www.hcn.zaq.ne.jp/___/DOM/ElementTraversal.html
 */
if ('defineProperty' in Object && (Element === 'function' || typeof Element === 'object') && 'prototype' in Element &&
    (!('firstElementChild' in document.createElement('p')) || !('lastElementChild' in document.createElement('p')) || !('previousElementSibling' in document.createElement('p')) || !('nextElementSibling' in document.createElement('p')) || !('childElementCount' in document.createElement('p')))) {

  (function (element, ELEMENT_NODE) {

    /**
     * Element.prototype.firstElementChild
     *  readonly attribute Element
     */
    if (!('firstElementChild' in element)) {
      this.defineProperty(Element.prototype, 'firstElementChild', {get: function () {
        var firstElementChild;

        firstElementChild = this.firstChild;

        while (firstElementChild) {
          if (firstElementChild.nodeType === ELEMENT_NODE) {
            break;
          }
          firstElementChild = firstElementChild.nextSibling;
        }

        return firstElementChild;
      }});
    }

    /**
     * Element.prototype.lastElementChild
     *  readonly attribute Element
     */
    if (!('lastElementChild' in element)) {
      this.defineProperty(Element.prototype, 'lastElementChild', {get: function () {
        var lastElementChild;

        lastElementChild = this.lastChild;

        while (lastElementChild) {
          if (lastElementChild.nodeType === ELEMENT_NODE) {
            break;
          }
          lastElementChild = lastElementChild.previousSibling;
        }

        return lastElementChild;
      }});
    }

    /**
     * Element.prototype.previousElementSibling
     *  readonly attribute Element
     */
    if (!('previousElementSibling' in element)) {
      this.defineProperty(Element.prototype, 'previousElementSibling', {get: function () {
        var previousElementSibling;

        previousElementSibling = this.previousSibling;

        while (previousElementSibling) {
          if (previousElementSibling.nodeType === ELEMENT_NODE) {
            break;
          }
          previousElementSibling = previousElementSibling.previousSibling;
        }

        return previousElementSibling;
      }});
    }

    /**
     * Element.prototype.nextElementSibling
     *  readonly attribute Element
     */
    if (!('nextElementSibling' in element)) {
      this.defineProperty(Element.prototype, 'nextElementSibling', {get: function () {
        var nextElementSibling;

        nextElementSibling = this.nextSibling;

        while (nextElementSibling) {
          if (nextElementSibling.nodeType === ELEMENT_NODE) {
            break;
          }
          nextElementSibling = nextElementSibling.nextSibling;
        }

        return nextElementSibling;
      }});
    }

    /**
     * Element.prototype.childElementCount
     *  readonly attribute Element
     */
    if (!('childElementCount' in element)) {
      this.defineProperty(Element.prototype, 'childElementCount', {get: function () {
        var childElementCount, childNodes, i, l;

        childElementCount = 0;
        childNodes = this.childNodes;

        for (i = 0, l = childNodes.length; i < l; i++) {
          if (childNodes[i].nodeType === ELEMENT_NODE) {
            childElementCount++;
          }
        }

        return childElementCount;
      }});
    }

  }).call(Object, document.createElement('p'), Node.ELEMENT_NODE);

}