The date string in 
 li: 2018-10-12, etc., after many times, the values are all taken out with js and modified to: 2018-10 "strong" 12 "/ strong", and finally the modified results are rewritten into the corresponding original tag, so that I can use css control to do a design style. I can only patchwork so that I can modify it after onclick. I don"t know how to change it automatically without mouse trigger. 
<ul id="news">
    <li><p class="time">2018-10-12</li>
    <li><p class="time">2017-08-03</li>
</ul>
<script>
//:replacePos(, , "");
function replacePos(strObj, pos, replacetext) {
    var str = strObj.substr(0, pos-1) + replacetext + strObj.substring(pos, strObj.length);
    return str;
}
//
function picnewsTime() {
    var obj = $(".time");//JQclasstime
    for(var i = 0; i < obj.length; iPP) {
          (function(arg){ 
            var txt = obj[arg].textContent || obj[arg].innerText;//
            var newhtml = replacePos(txt, 8, "<strong>");//replacePos()"-" <strong>
            newhtml += "</strong>";//</strong>
            //onclick
            obj[arg].onclick = function() {
                $(this).html(newhtml);//
            }
          })(i);//i
    }
}
picnewsTime();
</script>