Underscore js extend method

Question

Looks like Underscore library won't treat functions in JSON as first class citizens. Why doesn't this fiddle work?

http://jsfiddle.net/anV28/

var a = { 'f1': function(){var s='success';} };
var b = {'foo' : 'bar'};
var c = _.extend(b, a);
alert(JSON.stringify(c));

var d = _.extend({name : 'moe'}, {age : 50});
alert(JSON.stringify(d));

Why isn't c the right value?

d seems to have the right value if we only use strings as keys and values.

How can I get around this limitation?

Answer 1

c does have the right value:

{
    f1: function () {var s='success';},
    foo: "bar"
}

Your problem is that you're using JSON.stringify to produce strings for alert, there is no representation of a function in JSON so JSON.stringify(c) leaves f1 out. If you use console.log to view your results you'll have better luck: http://jsfiddle.net/ambiguous/7j7hu/

As an aside, you should keep in mind that using _.extend this way:

var c = _.extend(b, a);

will also modify b and that might not be your intent.