.. the Ecma spec considers a reference to eval to be a "direct eval call", but an expression that merely yields eval to be an indirect one -- and indirect eval calls are guaranteed to execute in global scope.
(While the following is [mostly] true, it is not specific to
The comma operator evaluates all the expressions and yields the value of the last expression.
(0, eval) evaluates to
eval (which is a function-object value), such that the resulting expression is equivalent to
To see it another way:
var f = (0, eval)
f === eval // true