title: using function expression with callback function instated of arrow function
body: <p>I have this code below works pretty well when I use arrow function as a callback function </p>
  
  <pre><code>var getNumber = function (argument, callback) {   
  callback(argument - 1);
  } 
  getNumber(10, (x)=&gt;{
  console.log(x); // x = 9
  });
  </code></pre>
  
  <p>now when I want to change the arrow function to function expression in the code below.</p>
  
  <pre><code>var getNumber = function (argument, callback) {
  callback(argument - 1);
  }
  getNumber(10, action(x)); // x is not defined 
  function action(x){
  console.log(x);
  }
  </code></pre>
  
  <p>sadly I got error says x is not defined.</p>