title: When does a transpiler (like babel) changes ecmascript6 code into ecmascript5 code?
body: <p>I am working with babel, maven, <code>angular 1.5</code> and <code>es6</code>. Came across with the concept of transpilers converting code written in <code>es6</code> internally into <code>es5</code> code for backward compatibility of browser. 
  Would like to know When does a transpiler (like <code>babel</code>) changes <code>ecmascript6</code> code into <code>ecmascript5</code> code ?</p>