javascript function don't pass cases

I have no idea why my function doesn't work in some cases:

function moveZeros(elem) {
  var count = 0;
  var a=elem;
  for (var i=0; i< elem.length; i++){
    if (elem[i]===0) {
    elem.splice(i,1);
    count++;
    }
  } 
  while (count>0) { 
    elem.push(0); 
    count--;
    }
    return  elem;
}

In moveZeros([1,2,0,1,0,1,0,3,0,1]) all good, but if case is:

moveZeros([9,0.0,0,9,1,2,0,1,0,1,0.0,3,0,1,9,0,0,0,0,9])

it returns

[9,0,9,1,2,1,1,3,1,9,0,0,9,0,0,0,0,0,0,0]

I case :

moveZeros(["a",0,0,"b","c","d",0,1,0,1,0,3,0,1,9,0,0,0,0,9]) it returns: ["a",0,"b","c","d",1,1,3,1,9,0,0,9,0,0,0,0,0,0,0]

Why not all zeros goes to the end ?