Javascript variable scoping with IIFE

Question

I'm new to Javascript and trying to loop over the array inside a for loop with a setTimeout this is a portion of code so i have 100msec by default. I'm expecting output to be 1,2,3 but all its printing is undefined 3 times. if someone can help me explaining why that will be helpful.

var allCars=['Car1','Car2','Car3'];
for(var i = 0; i < allCars.length; i++)
{
  (function(temp){  
  setTimeout(function(temp){
      console.log(allCars[temp]);
  },100)})(i);
}

Answer 1

setTimeout does not pass any parameter (unless you specify one) to its callback, but you're specifying one parameter named temp, which hides the temp in the outer scope.

var allCars=['Car1','Car2','Car3'];
for(var i = 0; i < allCars.length; i++)
{
  (function(temp){  
  setTimeout(function(temp){    // This temp hides the temp on the line above
      console.log(allCars[temp]);
  },100)})(i);
}

Simply remove the parameter from the callback passed to setTimeout to allow the outer temp to be visible.