If we're being nitpicky about type checking... function f() { return Math.random() < 0.5; } f.toString = function () { return 'function toArray() { [na

If we're being nitpicky about type checking... function f() { return Math.random() < 0.5; } f.toString = function () { return 'function toArray() { [native code] }' } Array.isArray = f; What, use Function.prototype.toString instead? What if someone tampered with that too?