渲染阻止CSS-延迟加载CSS文件

Question

i'm trying to solve render bloking for my site but have problem with them. i load css files with the following code:

<script>
  var loadDeferredStyles = function() {
    var addStylesNode = document.getElementById("deferred-styles");
    var replacement = document.createElement("div");
    replacement.innerHTML = addStylesNode.textContent;
    document.body.appendChild(replacement)
    addStylesNode.parentElement.removeChild(addStylesNode);
  };
  var raf = requestAnimationFrame || mozRequestAnimationFrame ||
      webkitRequestAnimationFrame || msRequestAnimationFrame;
  if (raf) raf(function() { window.setTimeout(loadDeferredStyles, 0); });
  else window.addEventListener('load', loadDeferredStyles);
</script>

<noscript id="deferred-styles">
  <link href="/template/styles/main.min.css" rel="stylesheet">    
  <link href="/template/styles/style.min.css" rel="stylesheet">
  <link href="/template/styles/bootstrap.min.css" rel="stylesheet">
  <link href="/template/styles/bootstrap-flipped.css" rel="stylesheet">
  <link href="/template/styles/swiper.min.css" rel="stylesheet" >
  <link href="/template/styles/fontiran.min.css" rel="stylesheet">
  <link href="/template/styles/font-awesome.min.css" rel="stylesheet">
  <link href="/template/styles/animate.min.css" rel="stylesheet">
  <link href="/template/styles/owl.carousel.css" rel="stylesheet">
  <link href="/template/styles/owl.transitions.css" rel="stylesheet">
  <link href="/template/styles/responsive.css" rel="stylesheet">
  <link href="/template/styles/theme-default.css" rel="stylesheet" type="text/css" />
</noscript>

but in "google page speed tools > insights" is render blocking css files. help me to resolve it ^_^

Answer 1

You can have different stylesheets for different media,

<link rel="stylesheet" media="mediatype and|not|only (media feature)" href="mystylesheet.css">
<link rel="stylesheet" media="screen and (max-height:700px)" href="style-max-700-height.css">

in media you can write like max-width, max-height,min-width,min-resolution see more at https://www.w3schools.com/cssref/css3_pr_mediaquery.asp and also https://www.w3schools.com/tags/att_link_media.asp

Answer 2

I think you need to add your CSS first and then run the JavaScript. You might be getting JavaScript errors on the console for this code.

<noscript id="deferred-styles">
  <link href="/template/styles/main.min.css" rel="stylesheet">    
  <link href="/template/styles/style.min.css" rel="stylesheet">
  <link href="/template/styles/bootstrap.min.css" rel="stylesheet">
  <link href="/template/styles/bootstrap-flipped.css" rel="stylesheet">
  <link href="/template/styles/swiper.min.css" rel="stylesheet" >
  <link href="/template/styles/fontiran.min.css" rel="stylesheet">
  <link href="/template/styles/font-awesome.min.css" rel="stylesheet">
  <link href="/template/styles/animate.min.css" rel="stylesheet">
  <link href="/template/styles/owl.carousel.css" rel="stylesheet">
  <link href="/template/styles/owl.transitions.css" rel="stylesheet">
  <link href="/template/styles/responsive.css" rel="stylesheet">
  <link href="/template/styles/theme-default.css" rel="stylesheet" type="text/css" />
</noscript>

<script>
  var loadDeferredStyles = function() {
    var addStylesNode = document.getElementById("deferred-styles");
    var replacement = document.createElement("div");
    replacement.innerHTML = addStylesNode.textContent;
    document.body.appendChild(replacement)
    addStylesNode.parentElement.removeChild(addStylesNode);
  };
  var raf = requestAnimationFrame || mozRequestAnimationFrame ||
      webkitRequestAnimationFrame || msRequestAnimationFrame;
  if (raf) raf(function() { window.setTimeout(loadDeferredStyles, 0); });
  else window.addEventListener('load', loadDeferredStyles);
</script>