Question

I try to load some js files dynamically,for example:

function openInforWindow(){
  //check if the InforWinow.js has been loaded or not
  if(window.InforWindow){
    //do the right thing
  }
  else {
    loadJs('xxxxxx/InforWindow.js');
    // do the right thing
    //but here ,the infowindow is not definded yet.
  }
}

function loadJs(filename){
  var fileref=document.createElement('script')
  fileref.setAttribute("type","text/javascript")
  fileref.setAttribute("src", filename)
  if (typeof fileref!="undefined")
  document.getElementsByTagName("head")[0].appendChild(fileref)
}

How to make sure that the vars or functions in the js which is dynamically loaded can be add to the javascript execute environment so I can use them ?

Answer 1

adding a script element isn’t a blocking operation, this means that your loadJs method returns immediately when your external script isn’t even loaded (nor interpreted). You have to wait for it to load.

function openInforWindow(){
  //check if the InforWinow.js has been loaded or not
  if(window.InforWindow){
    //do the right thing
  }
  else {
    var loadHandler = function() {
       //do stuff with inforWindow 
    };

    loadJs('xxxxxx/InforWindow.js', loadHandler);

  }
}

function loadJs(filename, handler){
  var fileref=document.createElement('script');
  fileref.setAttribute("type","text/javascript");
  fileref.setAttribute("src", "js");
  fileref.onreadystatechange = function () {
    if (this.readyState == 'complete')handler();
  };
  fileref.onload = handler;
  if (typeof fileref!="undefined")
  document.getElementsByTagName("head")[0].appendChild(fileref);
}