title: Can't understand function Javascript
body: <p>Hello everyone I am frontend beginner, so for me parallax scrolling is very interesting area, and now I start learning it. 
  I am watching tutorials and read a lot of stuff for it, but still I am filing as a beginner. 
  And now I have this: </p>
  
  <pre><code>if (wScroll &gt; $('.clothes-pics').offset().top - ($(window).height() / 1.2)) { 
  
  $('.clothes-pics figure').each(function(i){
  
  setTimeout(function(){ 
  
    $('.clothes-pics figure').eq(i).addClass('is-showing'); 
    }, (300 * (Math.exp(i * 0.15))) - 700); 
    }); 
  
  }
  </code></pre>
  
  <p>So here in this example i don't understand the <b>(300 * (Math.exp(i * 0.15))) - 700);  </b> code before it I can understand 85%, but here i don't know what is what, and  I am really confused. 
  If anyone can explain it to me i will be very thankful. <br>
  And If someone know some good tutorial for parallax it will be very welcome. </p>