title: JQuery-equivalent to prototypes Down()-function
body: <p>I'm porting a webapp from prototype to jquery in which I often used the prototype Down() function. (selecting the first child of a given element)</p>
  
  <p>Glancing over the JQuery-api one of the ways to do this would be: </p>
  
  <p>prototype: $('abc').down(); 
  jquery:    $('abc').children().first(); </p>
  
  <p>However, since this first fetches all children and applies a filter aferwards, I doubt it's efficient for this use-case. </p>
  
  <p>What's a better way? </p>