How to dynamically import static resource files such as js and css using javascript_javascript skills

The example in this article describes the method of dynamically importing static resource files such as js and css using javascript. Share it with everyone for your reference. The specific implementation method is as follows:

/**
 * 动态导入静态资源文件js/css
 */
var $import = function(){
  return function(rId, res, callback){
    if(res && 'string' == typeof res){
      if(rId){
        if($($('#' + rId), $('head')).length>0){
          return;
        }
      }
      //加载资源文件
      var sType = res.substring(res.lastIndexOf('.') + 1);
      // 支持js/css
      if(sType && ('js' == sType || 'css' == sType)){
        var isScript = (sType == 'js');
        var tag = isScript ? 'script' : 'link';
        var head = document.getElementsByTagName('head')[0];
        // 创建节点
        var linkScript = document.createElement(tag);
        linkScript.type = isScript ? 'text/javascript' : 'text/css';
        linkScript.charset = 'UTF-8';
        if(!isScript){
          linkScript.rel = 'stylesheet';
        }
        isScript ? linkScript.src = res : linkScript.href = res;
        if(callback && 'function' == typeof callback){
          if (linkScript.addEventListener){
            linkScript.addEventListener('load', function(){
              callback.call();
            }, false);
          } else if (linkScript.attachEvent) {
            linkScript.attachEvent('onreadystatechange', function(){
              var target = window.event.srcElement;
              if (target.readyState == 'complete') {
                callback.call();
              }
            });
          }
        }
        head.appendChild(linkScript);
      }
    }
  };
}();

I hope this article will be helpful to everyone’s JavaScript programming design.