hexo-theme-stellar/layout/_partial/cover/post_cover.ejs

<%
function div() {
  var el = '';
  if ((page.banner == undefined || page.banner == false) && !theme.article.auto_banner) {
    return el;
  }
  var url;
  if (page.banner != undefined) {
    if (page.banner.includes('/')) {
      url = page.banner;
    } else {
      url = 'https://source.unsplash.com/2000x400/?' + page.banner;
    }
  } else {
    // 自动以 tags 作为关键词搜索封面
    if (page.tags) {
      var params = '';
      page.tags.reverse().forEach((tag, i) => {
        if (i > 0) {
          params += ',';
        }
        params += tag.name;
      });
      url = 'https://source.unsplash.com/2000x400/?' + params;
    } else {
      url = 'https://source.unsplash.com/random/2000x400';
    }
  }
  el += '<div class="l_cover post' + scrollreveal(' ') + '">';
  el += '<div class="cover">';
  if (theme.plugins.lazyload && theme.plugins.lazyload.enable) {
    el += '<div class="lazy img bg" data-bg="' + url + '"></div>';
  } else {
    el += '<div class="lazy img bg" style="background-image:url(&quot;' + url + '&quot;)"></div>';
  }
  el += '</div>';
  el += '</div>';
  return el;
}
%>
<%- div() %>