Iframe.readyState does not work in chrome

Question

I create an Iframe on the fly and set as the url a page that downloads a binary file (xls, doc...). While files are downloading I show an animation. When do

Answer 1

The downloadable file content doesn't trigger the readystatechange event handler or the onload event handler. This couse you can set a cookie in server side together the file content, and client side check this cookie periodically. For example:

server

response.cookie('fileDownloaded','true');
response.header('attachment','your-file-name.any');
//...write bytes to response...

client

var checker = setInterval(()=>{
    if(document.cookie.indexOf('fileDownloaded')>-1){
        alert('done');
        clearInterval(checker);
    }
},100);

Of course, you can use your framework to check the cookie value correctly, this is just a poc, not a safe cookie parser.