This illustrates how JScript.NET fails to extend intrinsic object prototypes.

jscript-dot-net-fail.js

//jscript.net does not support extending intrinsic object prototypes

Object.prototype.foo = 1;

var x = {};
print("Object.prototype.foo -",Object.prototype.foo);    //should print 1. in jscript.net: undefined
print("x.foo - ",x.foo);                   //same


Object.prototype["foo"] = 1;

var y = {};
print("Object.prototype.foo - ",Object.prototype.foo);    //same
print("x.foo - ",x.foo);                   //same
print("y.foo - ",y.foo);                   //same

try {
    Array.prototype.bar = 2;    //this blows up
}catch(e){
    print("Exception :",e.message);
}

try {
    Array.prototype["bar"] = 2;    //this blows up
}catch(e){
    print("Exception :",e.message);
}

var z = [];

print("z.bar - ",z.bar);                                //undefined
print("Array.prototype.bar - ",Array.prototype.bar);    //undefined