title: Adding strings in JavaScript "1" + - "2" == "1-2"
body: <p>I accidentally typed the following JavaScript statement <code>"1" + - "2"</code> and I have the result <code>"1-2"</code>.
  I am not sure why the minus sign was treated as a string rather than causing a syntax error.  </p>
  
  <p>I tried to search, but I did not get the answer I wanted. </p>
  
  <p>Why the minus sign was treated as a string? it there online reference I can look at? thanks</p>