title: ES6 String interpolation from file content
body: <p>I came across the <a href="http://es6-features.org/#StringInterpolation" rel="noreferrer">String interpolation</a> feature in ES6. It works if I define the raw string in the code. But I want to read the raw string from a file and then replace the placeholders. How to do it?</p>
  
  <p><strong>file.txt</strong></p>
  
  <pre><code>   hello ${customer.name} 
  </code></pre>
  
  <p><strong>Node JS</strong></p>
  
  <pre><code>   var customer = {name: 'sid'};
     var data = fs.readFileSync("file.txt","utf8");
     // what should go here so that data is 'Hello sid'?
  </code></pre>