Tests for ES6 arrow function, calling of the super in arrow function On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS isReferenceError is true PASS b.id is value PASS isReferenceError is true PASS d1.id is "b" PASS d2.id is value PASS (new D()).id is value PASS (new E(false)).id is value PASS typeof (new E(true)).id is 'undefined' PASS (new F(false)).id is value PASS typeof (new F(true)).id is 'undefined' PASS indexOfParentClassInStackError < indexOfnestedArrowInStackError is true PASS indexOfnestedArrowInStackError < indexOfarrowInChildConstructorInStackError is true PASS indexOfarrowInChildConstructorInStackError < indexOfChildClassInStackError is true PASS indexOfChildClassInStackError > 0 is true PASS indexOfParentClassInStackError > -1 && errorStack.indexOf('ParentClass', indexOfParentClassInStackError + 1) === -1 is true PASS indexOfnestedArrowInStackError > -1 && errorStack.indexOf('nestedArrow', indexOfnestedArrowInStackError + 1) === -1 is true PASS indexOfarrowInChildConstructorInStackError > -1 && errorStack.indexOf('arrowInChildConstructor', indexOfarrowInChildConstructorInStackError + 1) === -1 is true PASS indexOfChildClassInStackError > -1 && errorStack.indexOf('ChildClass', indexOfChildClassInStackError + 1) === -1 is true PASS (new class extends A { constructor() { ((a = super())=>{})() } }).id is value PASS (new class extends A { constructor() { ((a = this)=>{ return a; })() } }) threw exception ReferenceError: 'super()' must be called in derived constructor before accessing |this| or returning non-object.. PASS (new class extends A { constructor() { ((a = this, b=super())=>{ return a; })() } }) threw exception ReferenceError: 'super()' must be called in derived constructor before accessing |this| or returning non-object.. PASS (new class extends A { constructor() { ((a = new.target)=>{ return a; })(); super(); } }) did not throw exception. PASS (new class extends A { constructor() { ((a = new.target, b=super())=>{ return a; })() } }) did not throw exception. PASS successfullyParsed is true TEST COMPLETE