eval、execScript、new Function和function效率比较

<script language="javascript">
var times = 10000

// --------------------------------
// eval
var b = new Date().getTime();
for (var i=0; i<times; i++)
{
	eval("var x=1;");
}
var e = new Date().getTime();
var p1 = e - b;

// --------------------------------
// execScript
var b = new Date().getTime();
for (var i=0; i<times; i++)
{
	execScript("var x=1;");
}
var e = new Date().getTime();
var p2 = e - b;

// --------------------------------
// new Function
var b = new Date().getTime();
for (var i=0; i<times; i++)
{
	new Function("var x=1;");
}
var e = new Date().getTime();
var p3 = e - b;

// --------------------------------
// function
var b = new Date().getTime();
for (var i=0; i<times; i++)
{
	function(){var x=1};
}
var e = new Date().getTime();
var p4 = e - b;

// --------------------------------
alert("eval 耗时 " + p1 + "毫秒， execScript 耗时 " + p2 + "毫秒， new Function 耗时 " + p3 + "毫秒， function 耗时 " + p4 + "毫秒");

</script>