[ZoNT]

var s = 'qwye r2ty qwww ert efger';
var myArray = s.split(' '); 
sm = myArray[0];
  for (var j=1; j<myArray.length; j++)
  {
    if (myArray[j].length<sm.length)
    {
        sm=myArray[j];
    }  
  }
   alert(sm)