javascript & call

1, Test call function of Array

var slice = Array.prototype.slice;

alert("slice.call(NaN).length:"+slice.call(NaN).length);  //  result : 0

alert("slice.call({0:'foo',length:'10',9:'2'})[0]:"+slice.call({0:'foo',length:'10',9:'2'})[0]);
// result : foo

alert("slice.call({0:'foo',length:'10',9:'2'})[9]:"+slice.call({0:'foo',length:'10',9:'2'})[9]);
// result : 2


alert("slice.call({0:'foo',length:'bar'})[0]:"+slice.call({0:'foo',length:'bar'})[0]); //result : undefined

So, function call(arg) , "arg" is Set of name/value pairs, set enclosed by a pair of curly braces{} , "length" is length of array, others are order number of array.


2, Mouse position
<script>
function mouseMove(ev)
{
 ev= ev || window.event;
  var mousePos = mouseCoords(ev);
  //alert(ev.pageX);
      document.getElementById('xxx').value = mousePos.x;
      document.getElementById('yyy').value = mousePos.y;
}
function mouseCoords(ev)
{
 if(ev.pageX || ev.pageY){
   return {x:ev.pageX, y:ev.pageY};
 }
 return {
     x:ev.clientX + document.body.scrollLeft - document.body.clientLeft,
     y:ev.clientY + document.body.scrollTop     - document.body.clientTop
 };
}
document.onmousemove = mouseMove;
</script>