A JavaScript Implementation of TreeWalker

TreeWalker.js

var NodeFilter = {
    FILTER_ACCEPT: 1,
    FILTER_REJECT: 2,
    FILTER_SKIP: 3,
    SHOW_ALL: -1,
    SHOW_ELEMENT: 1,
    SHOW_ATTRIBUTE: 2,
    SHOW_TEXT: 4,
    SHOW_CDATA_SECTION: 8,
    SHOW_ENTITY_REFERENCE: 16,
    SHOW_ENTITY: 32,
    SHOW_PROCESSING_INSTRUCTIONS: 64,
    SHOW_COMMENT: 128,
    SHOW_DOCUMENT: 256,
    SHOW_DOCUMENT_TYPE: 512,
    SHOW_DOCUMENT_FRAGMENT: 1024,
    SHOW_NOTATION: 2048
};

var TreeWalker = function (root, whatToShow, filter, expandEntityReferences) {
    this.root = root;
    this.whatToShow = whatToShow;
    this.filter = filter;
    this.expandEntityReferences = expandEntityReferences;
    this.currentNode = root;
    this.NodeFilter = NodeFilter;
};

TreeWalker.prototype.parentNode = function () {
    var testNode = this.currentNode;

    do {
        if (
            testNode !== this.root &&
            testNode.parentNode &&
            testNode.parentNode !== this.root
        ) {
            testNode = testNode.parentNode;
        } else {
            return null;
        }
    } while (this._getFilteredStatus(testNode) !== this.NodeFilter.FILTER_ACCEPT);
    (testNode) && (this.currentNode = testNode);

    return testNode;
};

TreeWalker.prototype.firstChild = function () {
    var testNode = this.currentNode.firstChild;

    while(testNode) {
        if(this._getFilteredStatus(testNode) === this.NodeFilter.FILTER_ACCEPT) {
            break;
        }
        testNode = testNode.nextSibling;
    }
    (testNode) && (this.currentNode = testNode);

    return testNode;
};

TreeWalker.prototype.lastChild = function () {
    var testNode = this.currentNode.lastChild;

    while (testNode) {
        if(this._getFilteredStatus(testNode) === this.NodeFilter.FILTER_ACCEPT) {
            break;
        }
        testNode = testNode.previousSibling;
    }
    (testNode) && (this.currentNode = testNode);

    return testNode;
};

TreeWalker.prototype.nextNode = function () {
    var testNode = this.currentNode;

    while (testNode) {
        if (testNode.childNodes.length !== 0) {
            testNode = testNode.firstChild;
        } else if (testNode.nextSibling) {
            testNode = testNode.nextSibling;
        } else {
            while (testNode) {
                if (testNode.parentNode && testNode.parentNode !== this.root) {
                    if (testNode.parentNode.nextSibling) {
                        testNode = testNode.parentNode.nextSibling;
                        break;
                    } else {
                        testNode = testNode.parentNode;
                    }
                }
                else return null;
            }
        }
        if (testNode && this._getFilteredStatus(testNode) === this.NodeFilter.FILTER_ACCEPT) {
            break;
        }
    }
    (testNode) && (this.currentNode = testNode);

    return testNode;
};

TreeWalker.prototype.previousNode = function () {
    var testNode = this.currentNode;

    while (testNode) {
        if (testNode.previousSibling) {
            testNode = testNode.previousSibling;
            while (testNode.lastChild) {
                testNode = testNode.lastChild;
            }
        }
        else {
            if (testNode.parentNode && testNode.parentNode !== this.root) {
                testNode = testNode.parentNode;
            }
            else testNode = null;
        }
        if (testNode && this._getFilteredStatus(testNode) === this.NodeFilter.FILTER_ACCEPT) {
            break;
        }
    }
    (testNode) && (this.currentNode = testNode);

    return testNode;
};

TreeWalker.prototype.nextSibling = function () {
    var testNode = this.currentNode;

    while(testNode) {
        (testNode.nextSibling) && (testNode = testNode.nextSibling);
        if(this._getFilteredStatus(testNode) === this.NodeFilter.FILTER_ACCEPT) {
            break;
        }
    }
    (testNode) && (this.currentNode = testNode);

    return testNode;
};

TreeWalker.prototype.previousSibling = function () {
    var testNode = this.currentNode;

    while(testNode) {
        (testNode.previousSibling) && (testNode = testNode.previousSibling);
        if(this._getFilteredStatus(testNode) == this.NodeFilter.FILTER_ACCEPT) {
            break;
        }
    }
    (testNode) && (this.currentNode = testNode);

    return testNode;
};

TreeWalker.prototype._getFilteredStatus = function (node) {
    var mask = ({
            /* ELEMENT_NODE */ 1: this.NodeFilter.SHOW_ELEMENT,
            /* ATTRIBUTE_NODE */ 2: this.NodeFilter.SHOW_ATTRIBUTE,
            /* TEXT_NODE */ 3: this.NodeFilter.SHOW_TEXT,
            /* CDATA_SECTION_NODE */ 4: this.NodeFilter.SHOW_CDATA_SECTION,
            /* ENTITY_REFERENCE_NODE */ 5: this.NodeFilter.SHOW_ENTITY_REFERENCE,
            /* ENTITY_NODE */ 6: this.NodeFilter.SHOW_PROCESSING_INSTRUCTION,
            /* PROCESSING_INSTRUCTION_NODE */ 7: this.NodeFilter.SHOW_PROCESSING_INSTRUCTION,
            /* COMMENT_NODE */ 8: this.NodeFilter.SHOW_COMMENT,
            /* DOCUMENT_NODE */ 9: this.NodeFilter.SHOW_DOCUMENT,
            /* DOCUMENT_TYPE_NODE */ 10: this.NodeFilter.SHOW_DOCUMENT_TYPE,
            /* DOCUMENT_FRAGMENT_NODE */ 11: this.NodeFilter.SHOW_DOCUMENT_FRAGMENT,
            /* NOTATION_NODE */ 12: this.NodeFilter.SHOW_NOTATION
        })[node.nodeType];

    return (
        (mask && (this.whatToShow & mask) == 0) ?
            this.NodeFilter.FILTER_REJECT :
            (this.filter && this.filter.acceptNode) ?
                this.filter.acceptNode(node) :
                this.NodeFilter.FILTER_ACCEPT
    );
};

if (!document.createTreeWalker) {
    document.createTreeWalker = function (root, whatToShow, filter, expandEntityReferences) {
        return new TreeWalker(root, whatToShow, filter, expandEntityReferences);
    };
}

Is this code free to use (under MIT)? I've been using this on an app, and I'd like to make sure our licenses are all in order.

This implementation appears to be lacking support for FILTER_SKIP. The Filter is supposed to return FILTER_SKIP instead of FILTER_REJECT. The behaviour is quite different (skipping is reject the node, but considering its children).

• http://www.w3.org/TR/dom/#concept-traversal-whattoshow
• http://www.w3.org/TR/dom/#concept-traverse-children

@dbalatero It's look like it's based on Mozile source code which has a "MPL 1.1/GPL 2.0/LGPL 2.1" licence