Caret index in nested node javascript

Question

I am trying to find the selection index of the caret inside a editable div that has nested nodes in it.

Example ( | is the cursor):

<div contenteditable="true">1234<span>5678|9</span></div> //Returns 4

I want the index of all the characters in the div, so the above example should return 8.

This is what I'm using at the moment.

var sel = window.getSelection();
    return sel.anchorOffset;

I have tried using commonAncestor, and other selection & range methods, but I am unsure how to find this.

Answer 1

Traverse the tree! Here’s a demo.

function getSelectionOffsetFrom(parent) {
    var sel = window.getSelection();
    var current = sel.anchorNode;
    var offset = sel.anchorOffset;

    while(current && current !== parent) {
        var sibling = current;

        while(sibling = sibling.previousSibling) {
            if(sibling.nodeType === 3) {
                offset += sibling.nodeValue.length;
            } else if(sibling.nodeType === 1) {
                offset += getContentLength(sibling);
            }
        }

        current = current.parentNode;
    }

    if(!current) {
        return null;
    }

    return offset;
}

function getContentLength(element) {
    var stack = [element];
    var total = 0;
    var current;

    while(current = stack.pop()) {
        for(var i = 0; i < current.childNodes.length; i++) {
            if(current.childNodes[i].nodeType === 1) {
                stack.push(current.childNodes[i]);
            } else if(current.childNodes[i].nodeType === 3) {
                total += current.childNodes[i].nodeValue.length;
            }
        }
    }

    return total;
}