为什么在屏幕上呈现用户选择?

Here is the plunker . 以下是简单的设置:

<p>Tim O'Reilly calls for a Blogger Code of Conduct. His proposals are:</p>
<ol>
    <li>Take responsibility not just for your own words, but for the
        comments you allow on your blog.</li>
    <li>Label your tolerance level for abusive comments.</li>
    <li>Consider eliminating anonymous comments.</li>
</ol>

<script>
    var range = document.createRange();
    var startPar = document.querySelector('p').firstChild;
    var endLi = document.querySelector('li:nth-child(2)').firstChild;
    range.setStart(startPar,13);
    range.setEnd(endLi,17);
    console.log(range.toString());
</script>

一切似乎都很好,我得到了预期的输出控制台,但文本并没有选择在屏幕上。这是故意的吗?