I removed the parenthesis from the following ternary:

```
res.setHeader('Content-Type', 'application/' + (isMap ? 'json' : 'javascript'));

```

And the test failed with:

```
Error: expected 'json' to equal 'application/javascript'

```

At first I thought this is just some wired Node.js issue, but it seems that:

```
'foo' + false ? 'bar' : 'baz'

```

Evaluates to 'bar' in Firefox and Chrome.

So my question is:

1. What happened to the first part of my string.
2. Why am I getting the `true` value of the ternary operation when I'm passing `false`.