Question

I made a simple **test **

i have 10 <p> elements.

after the first element i have a script :
which created 10 Iframes with SRc , and appending them to the first

element.

for (var i=0;i<10;i++)
     {
       var t=$("<iframe />").css({'width':'50px','height':'50px'}).attr('src','http://www.msdn.com');
        $("#hello").append(t);
      }

strange , but i do see the other 9 <p> , before the complete loading of the whole iframes…

should’nt the addition of new elements ( the iframes) into the Page elements should block subsequent html rendering ?
(plus , as we know , javascript is a single threaded )

Answer 1

No. JavaScript is single-threaded, but that doesn’t mean that the browser can’t launch more than one HTTP request concurrently. Consider that images also load via concurrent HTTP requests.

Adding an <iframe> to the document starts an HTTP request, but — because JavaScript is single-threaded — the code does not wait for that to finish.