How to know if there is a link element within the selection

问题

In Javascript, I'd like determine whether an element, say an A element, exists inside a given range/textRange. The aim is to determine if the user's current selection contains a link. I am building a rich text editor control.

The range object has a commonAncestorContainer (W3C) or parentElement() (Microsoft) method which returns the closest common anscestor of all elements in the range. However, looking inside this element for A elements won't work, since this common ancestor may also contain elements that aren't in the range, since the range can start or end part way through a parent.

How would you achieve this?

回答1:

How about selection.containsNode? https://developer.mozilla.org/en/DOM/Selection/containsNode

something like:

var selection = window.getSelection();
var range = selection.getRangeAt(0);
var result = $('a', range.commonAncestorContainer).filter(function() {
  return selection.containsNode(this);
});
console.log(result);

回答2:

I ended up going with a solution like this:

        var findinselection = function(tagname, container) {
            var
                i, len, el,
                rng = getrange(),
                comprng,
                selparent;
            if (rng) {
                selparent = rng.commonAncestorContainer || rng.parentElement();
                // Look for an element *around* the selected range
                for (el = selparent; el !== container; el = el.parentNode) {
                    if (el.tagName && el.tagName.toLowerCase() === tagname) {
                        return el;
                    }
                }
                // Look for an element *within* the selected range
                if (!rng.collapsed && (rng.text === undefined || rng.text) &&
                    selparent.getElementsByTagName) {
                    el = selparent.getElementsByTagName(tagname);
                    comprng = document.createRange ?
                        document.createRange() : document.body.createTextRange();
                    for (i = 0, len = el.length; i < len; i++) {

                        // determine if element el[i] is within the range
                        if (document.createRange) { // w3c
                            comprng.selectNodeContents(el[i]);
                            if (rng.compareBoundaryPoints(Range.END_TO_START, comprng) < 0 &&
                                rng.compareBoundaryPoints(Range.START_TO_END, comprng) > 0) {
                                return el[i];
                            }
                        }
                        else { // microsoft
                            comprng.moveToElementText(el[i]);
                            if (rng.compareEndPoints("StartToEnd", comprng) < 0 &&
                                rng.compareEndPoints("EndToStart", comprng) > 0) {
                                return el[i];
                            }
                        }
                    }
                }
            }
        };

Where getrange() is another function of mine to get the current selection as a range object.

To use, call it like

var link = findselection('a', editor);

Where editor is the contenteditable element, or body in a designmode iframe.

回答3:

This is a bit of a pain in the bum to do cross-browser. You could use my Rangy library, which is probably overkill for just this task but does make it more straightforward and works in all major browsers. The following code assumes only one Range is selected:

var sel = rangy.getSelection();
if (sel.rangeCount) {
    var range = sel.getRangeAt(0);
    var links = range.getNodes([1], function(node) {
        return node.tagName.toLowerCase() == "a" && range.containsNode(node);
    });
}

回答4:

I'm using this code that works with IE / Chrome / FF: (I'm using it to select rows <tr> in a table)

// yourLink is the DOM element you want to check
var selection = window.getSelection().getRangeAt(0)
var node = document.createRange()
node.selectNode(yourLink)
var s2s = selection.compareBoundaryPoints(Range.START_TO_END, node)
var s2e = selection.compareBoundaryPoints(Range.START_TO_START, node)
var e2s = selection.compareBoundaryPoints(Range.END_TO_START, node)
var e2e = selection.compareBoundaryPoints(Range.END_TO_END, node)
if ((s2s != s2e) || (e2s != e2e) || (s2s!=e2e))
    console.log("your node is inside selection")

回答5:

In the case of the range on the searched element, what I wrote is useful. (But only for that case!)

First I wrote a function that returns the Node found in the range: getNodeFromRange(rangeObject). Using this function it was already easy to write the function that returns the desired Node: findTagInRange(tagName).

function getNodeFromRange(range) {
    if(range.endContainer.nodeType==Node.ELEMENT_NODE) {
        return range.endContainer;
    }
    if(range.endContainer.nodeType==Node.TEXT_NODE) {
        return range.endContainer.parentNode;
    }
    else {
        // the 'startContainer' it isn't on an Element (<p>, <div>, etc...)
        return;
    }
}

function findTagInRange(tagName, range) {
    var node = getNodeFromRange(range);
    if(node && typeof(node.tagName)!='undefiend' && node.tagName.toLowerCase()==tagName.toLowerCase()) {
        return $(node);
    }
    return;
}

And then I can use it as follows: