Js judgment CSS file load finished concrete implementation

To judge whether the CSS file is loaded or not, there are big differences among browsers. This time, to say that Internet explorer has done a good job, we can directly use the onload method to deal with the processing of CSS after loading:

//Excerpt to seajs
function styleOnload(node, callback) {
    // for IE6-9 and Opera
    if (node.attachEvent) {
      node.attachEvent('onload', callback);
      // NOTICE:
      // 1. "onload" will be fired in IE6-9 when the file is 404, but in
      // this situation, Opera does nothing, so fallback to timeout.
      // 2. "onerror" doesn't fire in any browsers!
    }
} 

Unfortunately, this time in other browsers, it is not so convenient to determine whether the CSS is loaded, FF,webkit can determine whether the load is finished by the existence of the node.sheet. CssRules property. And you need to use setTimeout to interval event polling:

//Excerpt to seajs
function poll(node, callback) {
    if (callback.isCalled) {
      return;
    }
    var isLoaded = false;
    if (/webkit/i.test(navigator.userAgent)) {//webkit
      if (node['sheet']) {
        isLoaded = true;
      }
    }
    // for Firefox
    else if (node['sheet']) {
      try {
        if (node['sheet'].cssRules) {
          isLoaded = true;
        }
      } catch (ex) {
        // NS_ERROR_DOM_SECURITY_ERR
        if (ex.code === 1000) {
          isLoaded = true;
        }
      }
    }
    if (isLoaded) {
      // give time to render.
      setTimeout(function() {
        callback();
      }, 1);
    }
    else {
      setTimeout(function() {
        poll(node, callback);
      }, 1);
    }
  } 

setTimeout(function() {
     poll(node, callback);
}, 0); 

The complete treatment given by SeaJS is as follows:

function styleOnload(node, callback) {
    // for IE6-9 and Opera
    if (node.attachEvent) {
      node.attachEvent('onload', callback);
      // NOTICE:
      // 1. "onload" will be fired in IE6-9 when the file is 404, but in
      // this situation, Opera does nothing, so fallback to timeout.
      // 2. "onerror" doesn't fire in any browsers!
    }
    // polling for Firefox, Chrome, Safari
    else {
      setTimeout(function() {
        poll(node, callback);
      }, 0); // for cache
    }
  }
  function poll(node, callback) {
    if (callback.isCalled) {
      return;
    }
    var isLoaded = false;
    if (/webkit/i.test(navigator.userAgent)) {//webkit
      if (node['sheet']) {
        isLoaded = true;
      }
    }
    // for Firefox
    else if (node['sheet']) {
      try {
        if (node['sheet'].cssRules) {
          isLoaded = true;
        }
      } catch (ex) {
        // NS_ERROR_DOM_SECURITY_ERR
        if (ex.code === 1000) {
          isLoaded = true;
        }
      }
    }
    if (isLoaded) {
      // give time to render.
      setTimeout(function() {
        callback();
      }, 1);
    }
    else {
      setTimeout(function() {
        poll(node, callback);
      }, 1);
    }
  }
//My dynamically created LINK function
function createLink(cssURL,lnkId,charset,media){ 
    var head = document.getElementsByTagName('head')[0],
        linkTag = null;

 if(!cssURL){
     return false;
 }

    linkTag = document.createElement('link');
 linkTag.setAttribute('id',(lnkId || 'dynamic-style'));
 linkTag.setAttribute('rel','stylesheet');
 linkTag.setAttribute('charset',(charset || 'utf-8'));
 linkTag.setAttribute('media',(media||'all'));
 linkTag.setAttribute('type','text/css');
    linkTag.href = cssURL; 

    head.appendChild(linkTag); 
}
function loadcss(){
    var styleNode = createLink('/wp-content/themes/BlueNight/style.css');

    styleOnload(styleNode,function(){
        alert("loaded");
    });
}

When I saw the seajs code, I immediately remembered that I had seen another solution for Diego Perini:

/*
 * Copyright (C) 2010 Diego Perini
 * All rights reserved.
 *
 * cssready.js - CSS loaded/ready state notification
 *
 * Author: Diego Perini <diego.perini at gmail com>
 * Version: 0.1
 * Created: 20100616
 * Release: 20101104
 *
 * License:
 *  //www.jb51.net * Download:
 *  http://javascript.nwbox.com/cssready/cssready.js
 */
function cssReady(fn, link) {
  var d = document,
  t = d.createStyleSheet,
  r = t ? 'rules' : 'cssRules',
  s = t ? 'styleSheet' : 'sheet',
  l = d.getElementsByTagName('link');
  // passed link or last link node
  link || (link = l[l.length - 1]);
  function check() {
    try {
      return link && link[s] && link[s][r] && link[s][r][0];
    } catch(e) {
      return false;
    }
  }
  (function poll() {
    check() && setTimeout(fn, 0) || setTimeout(poll, 100);
  })();
}