var a; var b; var c; var d; var x; var y; Object.assign(Object.assign(Object.assign({ x }, y), {}, { a }, b), {}, { c }); Object.assign({}, Object.prototype); Object.assign({}, { foo: 'bar' }); Object.assign(Object.assign({}, { foo: 'bar' }), { bar: 'baz' }); Object.assign({}, { get foo() { return 'foo'; } });