title: Babel do not convert to ES5 if NodeJS is supported
body: <p>English is not my native language, please excuse typing errors.</p>
  
  <p>NodeJS LTS now 4.x and 6.x, which is part of the ES6 syntax is only supported in 6.x, <a href="http://node.green/" rel="nofollow noreferrer">node.green</a>.</p>
  
  <p>I have a back-end Node project needs to support the Node 4.x version now, but I have to used some syntax only worked in 6.x version. So I introduced Babel with <code>preset-es2015</code>. But with this preset, Babel transform from ES6 to ES5.</p>
  
  <p>ES6 part of the syntax, such as <code>const</code>, <code>let</code> the performance is higher than var (This is a hypothesis, the actual situation certainly not so simple).</p>
  
  <p>My code is running on ES6 support at 99% of Node 6.x or 57% of Node 4.x, there is really not need to downgrade all code to ES5.</p>
  
  <p>So I would like to know how to let Babel don't convert ES6 syntax to ES5 if NodeJS is supported.</p>
  
  <p>Further, does Babel support detecting code support for the current operating environment and intelligently converting it?</p>
  
  <p>Thank you.</p>
  
  <p>UPDATE: <a href="https://github.com/babel/babel-preset-env" rel="nofollow noreferrer"><code>babel-preset-env</code></a> is what I want.</p>