How to pass argument to javascript anonymous function -

Can anyone explain to me why X is undefined? 123 should not be?

  doSomething = (function (x) {warning (x)}) (); DoSomething (123);    
 
 
  doSomething  function is not  undefined < / Code>. 
 
  doSomething = (function (x) {warning (x)}) ();  
 
 This announces an anonymous function,  immediately  executes it (this is what  ()  does) Then sets   for return value -  undefined . Your anonymous function takes a parameter ( x ), but nothing is given to it, so  x  is  undefined . 
 
 You might want to: 
 
  doSomething = function (x) {warning (x)}; DoSomething (123);