跨浏览器比较文档位置

Question

DOM4 compareDocumentPosition

我想实现compareDocumentPosition.Resig 在这方面做了一个很好的开端.我已经把他的代码整理好了

function compareDocumentPosition(other) {
    var ret = 0;
    if (this.contains) {
        if (this !== other && this.contains(other)) {
            ret += 16;
        }
        if (this !== other && other.contains(this)) {
            ret += 8;
        }
        if (this.sourceIndex >= 0 && other.sourceIndex >= 0) {
            if (this.sourceIndex < other.sourceIndex) {
                ret += 4;
            }
            if (this.sourceIndex > other.sourceIndex) {
                ret += 2;
            }
        } else {
            ret += 1;
        }
    } 
    return ret;
}

这适用于Element但不适用于Text或DocumentFragment.这是因为IE8没有给出.sourceIndex那些节点.(它也没有给出.contains,但我已经解决了这个问题)

如何有效地写入+=4与DOCUMENT_POSITION_FOLLOWING和DOCUMENT_POSITION_PRECEDING+=2对应的位和位.

为了额外的参考,这两个是由DOM4定义的树顺序定义的

如果A和B在同一树中并且A以树顺序出现在B之前,则对象A在对象B之前.

如果A和B在同一树中,并且A以树顺序出现在B之后,则对象A跟随对象B.

树顺序是预订,深度优先遍历.

大多数现代浏览器都实现了这一点(包括IE9).所以你只需要在IE8中运行的东西(我不关心IE6/7,但它是否真的很棒!)

Answer 1

function recursivelyWalk(nodes, cb) {
    for (var i = 0, len = nodes.length; i < len; i++) {
        var node = nodes[i];
        var ret = cb(node);
        if (ret) {
            return ret;
        }
        if (node.childNodes && node.childNodes.length) {
            var ret = recursivelyWalk(node.childNodes, cb);
            if (ret) {
                return ret;
            }
        }
    }
}

function testNodeForComparePosition(node, other) {
    if (node === other) {
        return true;
    }
}

function compareDocumentPosition(other) {
    function identifyWhichIsFirst(node) {
        if (node === other) {
            return "other";
        } else if (node === reference) {
            return "reference";
        }
    }

    var reference = this,
        referenceTop = this,
        otherTop = other;

    if (this === other) {
        return 0;
    }
    while (referenceTop.parentNode) {
        referenceTop = referenceTop.parentNode;
    }
    while (otherTop.parentNode) {
        otherTop = otherTop.parentNode;
    }

    if (referenceTop !== otherTop) {
        return Node.DOCUMENT_POSITION_DISCONNECTED;
    }

    var children = reference.childNodes;
    var ret = recursivelyWalk(
        children,
        testNodeForComparePosition.bind(null, other)
    );
    if (ret) {
        return Node.DOCUMENT_POSITION_CONTAINED_BY +
            Node.DOCUMENT_POSITION_FOLLOWING;
    }

    var children = other.childNodes;
    var ret = recursivelyWalk(
        children, 
        testNodeForComparePosition.bind(null, reference)
    );
    if (ret) {
        return Node.DOCUMENT_POSITION_CONTAINS +
            Node.DOCUMENT_POSITION_PRECEDING;
    }

    var ret = recursivelyWalk(
        [referenceTop],
        identifyWhichIsFirst
    );
    if (ret === "other") {
        return Node.DOCUMENT_POSITION_PRECEDING;
    } else {
        return Node.DOCUMENT_POSITION_FOLLOWING;
    }
}

我自己写的.我认为这个实现被窃听了,但这是我的其他一些代码中的一个错误.看起来很稳固.