Example of JavaScript asyncronous nature

async.js

for (var i = 0; i < 10; i++ ){

  setTimeout( function() { 
    console.log( "value is " + i);
  }, 1000);
  
}

// what will the output be? 
// go to https://goo.gl/lFkgcr to run the code

// setTimeout will call the first argument, a function, at the specified milliseconds.
// it's asyncronous, so the code around it is going to keep running in the meantime