title: nodejs need use 'strict use'?or what is the best practice of node's strict mode?
body: <p>I'm a new to node.js and javascript.I checked code examples of node.js and it used <code>use strict</code> mode.</p>
  
  <p>For example, a server.js:</p>
  
  <pre><code>'use strict';
  //some server code
  </code></pre>
  
  <p>Also, I got to know that <code>use strict</code> is present at head of every js file.
  It confused me and so I want to know what is best practice in Nodejs to use strict mode?</p>
  
  <hr>
  
  <p>Thank you all, My question is focus on the strict mode. In this mode, some code mistake can be reported. In back-end, the strict error reporter also run? And If I need use it, I should add it in every js file header? Or add it in main file(server.js or etc.) head? Or use some node.js self style?</p>