Why is this alert not executing in the if-statement

This program should display an alert Found it on the 4th iteration

var animals = ["horse", "ox", "cow", "pig", "duck"];  
var i = 0;  
while (i < animals.length) {  
  if (animals.slice(i, i + 1) === "pig") {  
      alert("Found it");  
      break;  
  }  
 i++;  
}