ContentEditable 要素の末尾にキャレットを移動するにはどうすればよいですか?

function setEndOfContenteditable(contentEditableElement) {
    // Determine browser support
    var range, selection;
    if (document.createRange) {
        // Modern browsers
        range = document.createRange();
        range.selectNodeContents(contentEditableElement);
        range.collapse(false); // Collapse to end of range
        selection = window.getSelection();
        selection.removeAllRanges();
        selection.addRange(range);
    } else if (document.selection) {
        // IE 8 and lower
        range = document.body.createTextRange();
        range.moveToElementText(contentEditableElement);
        range.collapse(false); // Collapse to end of range
        range.select();
    }
}

elem = document.getElementById('txt1');
setEndOfContenteditable(elem);