extend-proto-issues.html

<!DOCTYPE>
<script type="text/javascript">
Object.prototype.a = "a";
Array.prototype.c = "c";

var o = {b: "b"};
for (var k in o) {
  alert("obj key: " + k);
}
// expected: b
// actual:   b,a

var arr = [1];
for (var k in arr) {
  alert("arr key: " + k);
}
// expected: 0
// actual:   0,c,a

for each (var v in arr) {
 alert("arr val: " + v);
}
// expected: 1
// actual:   1,c,a

</script>