转义字符变成html内容

转义字符互转

<div id="my"></div>
    <div id="he" style="display:none"></div>
    <script>
        var str = '&lt;h1&gt;这是标签&lt;/h1&gt;';
        document.getElementById('he').innerHTML = str;
        alert(str)
        var newstr = document.getElementById('he').innerText;
        document.getElementById('my').innerHTML = newstr

    </script>