Error calling forEach on an array literal in javascript

This code generates an error when I run it with node v6.9.2

var req = {}

['foo', 'bar'].forEach(prop => {
    console.log("prop: " + prop)
});

The error is: TypeError: Cannot read property 'forEach' of undefined

Why would that be? There doesn't seem to be anything syntactically wrong with what I'm doing. I note that if I add a semi-colon after the var req = {} line the error disappears, but I still don't understand why since I thought semi-colons were optional in JavaScript as long as each statement was on a separate line.

via rmacqueen