title: How String.concat() implements in javascript?
body: <p>In function <code>.concat()</code>, I can pass an arbitrary number of arguments to it.</p>
  
  <p>I understand function overloading in C++, but I don't know how implement a function with unknown number of arguments in JavaScript.</p>
  
  <p>How do I implement an arbitrary number of arguments to a function?</p>