JS: Get and set the position of a carat/cursor for an element.

getCarat.js

function _getCarat(el) {

    if (el.selectionStart) {
        return el.selectionStart;
    } else if (document.selection) {
        el.focus();

        var r = document.selection.createRange();
        if (r == null) {
            return 0;
        }

        var re = el.createTextRange(),
            rc = re.duplicate();
            re.moveToBookmark(r.getBookmark());
            rc.setEndPoint('EndToStart', re);

        return rc.text.length;
    }
    return 0;
}

setCarat.js

function _setCarat(el, start, end) {
    if (typeof start == 'string' && start === 'end') {
        start = el.value.length;
    }
    end = end || start;
    el.setSelectionRange(start, end);
}