jquery - javascript - setTimeout return

Question

How can I use setTimeout if I want to return a value

$.each(pCodes, function(index, pCode) {
    setTimeout(func(parm1), 2000);      
});


function func(in)
{
  var value = 999;
  return value;
}

Answer 1

First of all, your call to setTimeout is wrong. You are calling the function func and then using the result in the setTimeout method. Your code is equivalent to:

$.each(pCodes, function(index, pCode) {
  var temp = func(parm1);
  setTimeout(temp, 2000);      
});

As func returns 999, you will be doing setTimeout(999, 2000), which of course doesn't make sense. To call a function that takes a parameter from setTimeout you need a function that makes that function call:

$.each(pCodes, function(index, pCode) {
  setTimeout(function() { func(parm1); }, 2000);
});

To handle the return value from func is a bit more complicated. As it's called later on, you have to handle the return value later on. Usually that is done with a callback method that is called when the return value is available:

var callback = function(value) {
  // Here you can use the value.
};
$.each(pCodes, function(index, pCode) {
  setTimeout(function() { func(parm1, callback); }, 2000);
});

function func(in, callback) {
  var value = 999;
  callback(value);
}