var foo = {}; mutate1( foo ); // should be included [ 'a', 'b', 'c' ].forEach( function ( letter, i ) { foo[ letter ] = i; }); [ 'd', 'e', 'f' ].forEach( ( letter, i ) => { foo[ letter ] = i; }); function mutate1 () { foo.mutated = 1; } ({ mutate2: function () { foo.mutated = 2; } }).mutate2(); // should be excluded var mutate2 = function () { foo.mutated = 2; } function unused1 () { foo.wat = 'nope'; } function unused2 () { mutate1( foo ); } export default foo;