<!DOCTYPE html>
<html>
<head><title>JavaScript Introspection</title></head>
<body>
<script>
var x;
function introspect(object)
{
var type = Object.prototype.toString.call(object);
switch(type){
case '[object Array]':
x = "array";
break;
case '[object Object]':
x = "object";
break;
case '[object String]':
x = "string";
break;
case '[object Number]':
x = "number";
break;
case '[object Boolean]':
x= "boolean";
break;
case '[object Date]':
x= "date";
break;
case '[object Undefined]':
x= "undefined";
break;
case '[object Null]':
x= "null";
break;
default:
x ="not recognized";
}}
introspect(["one","two","three"]);
document.write(x);
</script></body>
</html>Para obter mais detalhes, consulte: http://sketchytech.blogspot.co.uk/2013/02/introspection-in-javascript.html