打字稿与JavaScript语法

Question

I am trying to take some javascript and translate it into typescript in order to use it with a webpage that will utilize Aurelia. I am having some syntax issues with the below lines. If anyone can point me in the right direction on this would be most appreciated. Lines are below. Thanks in advance

--Jason

//trying to see if the browser supports HTML5 FileReader functionality
//VS currently says filereader does not exist on type 'Window'
      if (window.filereader) 

//VS says Property 'trigger' does not exist on type 'HTMLElement'
      document.getElementById('fileBox').trigger('click');

//VS says Property 'click' does not exist on type 'Element'
       document.querySelector('.fileCont span').click(function () {
    this.remove();
});


  // Property 'file' does not exist on type 'HTMLImageElement'
     var img = document.createElement("img");
     img.file = file;

Answer 1

For types that haven't yet made it into the standard definition file, you can extend the interface to include the additional properties :

interface Window {
    filereader: any;
}

if (window.filereader) {

} 

If you are using a library, for example jQuery, you can grab a ready-made definition for that .