networks sux and browsers may surprise you

gistfile1.txt

index.html
...
<script src="a.js"></script>
<script src="b.js"></script>
<script src="c.js"></script>

a.js:
var globalfoo = 42;

b.js:
<whatever>

c.js:
// one of three things may happen in c.js:
// 1. it does not load (so does not execute)
// 2. it prints 42
// 3. it throws ReferenceError: globalfoo is not defined
console.log(globalfoo);