Will setInterval cause browsers to hang?

Question

A couple years ago I was warned against using setInterval for long periods of time as it supposedly would cause the browser to hang if the called function ran l

Answer 1

The reason setInterval is bad is because it will try to execute the code every X MS regardless of what's going on in the thread. So if you have:

setInterval( complexFunction, 1 ); // complexFunction takes >1 MS to complete

...you may end up with setInterval trying to re-execute several times before even its own code is complete! However, you can use setTimeout similarly and avoid this problem:

setTimeout( complexFunction, 1 );

function complexFunction() {
  // complex code
  setTimeout( complexFunction, 1 );
}

...now complexFunction will only call itself again once its own code is complete, so if its own code takes longer than 1 MS to complete you won't have any backlog to deal with like you would with setInterval

Answer 2

it always better to use setTimeout in a loop so you know exactly when to continue timing:

foo();
function foo(){

   setTimeout (function(){
      foo = 'bar_' + i++;
      foo();
     }, 1 );

} 

otherwise as you said above, the browser will have to catch up and since ur loop is in infinitum, it might not.