Tests for ES6 class name semantics in class statements and expressions On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". Class statement PASS A:::ReferenceError: Can't find variable: A PASS 'use strict'; A:::ReferenceError: Can't find variable: A PASS class {}:::SyntaxError: Class statements must have a name. PASS 'use strict'; class {}:::SyntaxError: Class statements must have a name. PASS class { constructor() {} }:::SyntaxError: Class statements must have a name. PASS 'use strict'; class { constructor() {} }:::SyntaxError: Class statements must have a name. PASS class A { constructor() {} } PASS 'use strict'; class A { constructor() {} } PASS class A { constructor() {} }; A.toString():::'class A { constructor() {} }' PASS 'use strict'; class A { constructor() {} }; A.toString():::'class A { constructor() {} }' PASS class A { constructor() {} }; (new A) instanceof A PASS 'use strict'; class A { constructor() {} }; (new A) instanceof A PASS class A { constructor() { this.base = A; } }; (new A).base.toString():::'class A { constructor() { this.base = A; } }' PASS 'use strict'; class A { constructor() { this.base = A; } }; (new A).base.toString():::'class A { constructor() { this.base = A; } }' PASS class A { constructor() {} }; class B extends A {}; PASS 'use strict'; class A { constructor() {} }; class B extends A {}; PASS class A { constructor() {} }; class B extends A { constructor() {} }; B.toString():::'class B extends A { constructor() {} }' PASS 'use strict'; class A { constructor() {} }; class B extends A { constructor() {} }; B.toString():::'class B extends A { constructor() {} }' PASS class A { constructor() {} }; class B extends A {}; (new B) instanceof A PASS 'use strict'; class A { constructor() {} }; class B extends A {}; (new B) instanceof A PASS class A { constructor() {} }; class B extends A {}; (new B) instanceof B PASS 'use strict'; class A { constructor() {} }; class B extends A {}; (new B) instanceof B PASS class A { constructor() {} }; class B extends A { constructor() { super(); this.base = A; this.derived = B; } }; (new B).base.toString():::'class A { constructor() {} }' PASS 'use strict'; class A { constructor() {} }; class B extends A { constructor() { super(); this.base = A; this.derived = B; } }; (new B).base.toString():::'class A { constructor() {} }' PASS class A { constructor() {} }; class B extends A { constructor() { super(); this.base = A; this.derived = B; } }; (new B).derived.toString():::'class B extends A { constructor() { super(); this.base = A; this.derived = B; } }' PASS 'use strict'; class A { constructor() {} }; class B extends A { constructor() { super(); this.base = A; this.derived = B; } }; (new B).derived.toString():::'class B extends A { constructor() { super(); this.base = A; this.derived = B; } }' Class expression PASS A:::ReferenceError: Can't find variable: A PASS 'use strict'; A:::ReferenceError: Can't find variable: A PASS (class {}) PASS 'use strict'; (class {}) PASS (class { constructor(){} }) PASS 'use strict'; (class { constructor(){} }) PASS typeof (class {}):::"function" PASS 'use strict'; typeof (class {}):::"function" PASS (class A {}) PASS 'use strict'; (class A {}) PASS typeof (class A {}):::"function" PASS 'use strict'; typeof (class A {}):::"function" PASS (class A {}); A:::ReferenceError: Can't find variable: A PASS 'use strict'; (class A {}); A:::ReferenceError: Can't find variable: A PASS new (class A {}) PASS 'use strict'; new (class A {}) PASS typeof (new (class A {})):::"object" PASS 'use strict'; typeof (new (class A {})):::"object" PASS (new (class A { constructor() { this.base = A; } })).base PASS 'use strict'; (new (class A { constructor() { this.base = A; } })).base PASS (new (class A { constructor() { this.base = A; } })).base.toString():::"class A { constructor() { this.base = A; } }" PASS 'use strict'; (new (class A { constructor() { this.base = A; } })).base.toString():::"class A { constructor() { this.base = A; } }" PASS class A {}; (class B extends A {}) PASS 'use strict'; class A {}; (class B extends A {}) PASS class A {}; (class B extends A {}); B:::ReferenceError: Can't find variable: B PASS 'use strict'; class A {}; (class B extends A {}); B:::ReferenceError: Can't find variable: B PASS class A {}; new (class B extends A {}) PASS 'use strict'; class A {}; new (class B extends A {}) PASS class A {}; new (class B extends A { constructor() { super(); this.base = A; this.derived = B; } }) PASS 'use strict'; class A {}; new (class B extends A { constructor() { super(); this.base = A; this.derived = B; } }) PASS class A {}; (new (class B extends A { constructor() { super(); this.base = A; this.derived = B; } })) instanceof A PASS 'use strict'; class A {}; (new (class B extends A { constructor() { super(); this.base = A; this.derived = B; } })) instanceof A PASS class A { constructor() {} }; (new (class B extends A { constructor() { super(); this.base = A; this.derived = B; } })).base.toString():::'class A { constructor() {} }' PASS 'use strict'; class A { constructor() {} }; (new (class B extends A { constructor() { super(); this.base = A; this.derived = B; } })).base.toString():::'class A { constructor() {} }' PASS class A { constructor() {} }; (new (class B extends A { constructor() { super(); this.base = A; this.derived = B; } })).derived.toString():::'class B extends A { constructor() { super(); this.base = A; this.derived = B; } }' PASS 'use strict'; class A { constructor() {} }; (new (class B extends A { constructor() { super(); this.base = A; this.derived = B; } })).derived.toString():::'class B extends A { constructor() { super(); this.base = A; this.derived = B; } }' Class expression assignment to variable PASS A:::ReferenceError: Can't find variable: A PASS 'use strict'; A:::ReferenceError: Can't find variable: A PASS var VarA = class {} PASS 'use strict'; var VarA = class {} PASS var VarA = class { constructor() {} }; VarA.toString():::'class { constructor() {} }' PASS 'use strict'; var VarA = class { constructor() {} }; VarA.toString():::'class { constructor() {} }' PASS VarA:::ReferenceError: Can't find variable: VarA PASS 'use strict'; VarA:::ReferenceError: Can't find variable: VarA PASS var VarA = class A { constructor() {} } PASS 'use strict'; var VarA = class A { constructor() {} } PASS var VarA = class A { constructor() {} }; VarA.toString():::'class A { constructor() {} }' PASS 'use strict'; var VarA = class A { constructor() {} }; VarA.toString():::'class A { constructor() {} }' PASS var VarA = class A { constructor() {} }; A.toString():::ReferenceError: Can't find variable: A PASS 'use strict'; var VarA = class A { constructor() {} }; A.toString():::ReferenceError: Can't find variable: A PASS var VarA = class A { constructor() {} }; (new VarA) instanceof VarA PASS 'use strict'; var VarA = class A { constructor() {} }; (new VarA) instanceof VarA PASS var VarA = class A { constructor() { this.base = A; } }; (new VarA).base.toString():::'class A { constructor() { this.base = A; } }' PASS 'use strict'; var VarA = class A { constructor() { this.base = A; } }; (new VarA).base.toString():::'class A { constructor() { this.base = A; } }' PASS var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() {} }; PASS 'use strict'; var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() {} }; PASS var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() {} }; B:::ReferenceError: Can't find variable: B PASS 'use strict'; var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() {} }; B:::ReferenceError: Can't find variable: B PASS var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() {} }; VarB.toString():::'class B extends VarA { constructor() {} }' PASS 'use strict'; var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() {} }; VarB.toString():::'class B extends VarA { constructor() {} }' PASS var VarA = class A { constructor() {} }; var VarB = class B extends VarA { }; (new VarB) instanceof VarA PASS 'use strict'; var VarA = class A { constructor() {} }; var VarB = class B extends VarA { }; (new VarB) instanceof VarA PASS var VarA = class A { constructor() {} }; var VarB = class B extends VarA { }; (new VarB) instanceof VarB PASS 'use strict'; var VarA = class A { constructor() {} }; var VarB = class B extends VarA { }; (new VarB) instanceof VarB PASS var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() { super(); this.base = VarA; this.derived = B; this.derivedVar = VarB; } }; (new VarB).base === VarA PASS 'use strict'; var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() { super(); this.base = VarA; this.derived = B; this.derivedVar = VarB; } }; (new VarB).base === VarA PASS var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() { super(); this.base = VarA; this.derived = B; this.derivedVar = VarB; } }; (new VarB).derived === VarB PASS 'use strict'; var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() { super(); this.base = VarA; this.derived = B; this.derivedVar = VarB; } }; (new VarB).derived === VarB PASS var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() { super(); this.base = VarA; this.derived = B; this.derivedVar = VarB; } }; (new VarB).derivedVar === VarB PASS 'use strict'; var VarA = class A { constructor() {} }; var VarB = class B extends VarA { constructor() { super(); this.base = VarA; this.derived = B; this.derivedVar = VarB; } }; (new VarB).derivedVar === VarB Class statement binding in other circumstances PASS var result = A; result:::ReferenceError: Can't find variable: A PASS 'use strict'; var result = A; result:::ReferenceError: Can't find variable: A PASS var result = A; class A {}; result:::ReferenceError: Cannot access uninitialized variable. PASS 'use strict'; var result = A; class A {}; result:::ReferenceError: Cannot access uninitialized variable. PASS class A { constructor() { A = 1; } }; new A:::TypeError: Attempted to assign to readonly property. PASS 'use strict'; class A { constructor() { A = 1; } }; new A:::TypeError: Attempted to assign to readonly property. PASS class A { constructor() { } }; A = 1; A:::1 PASS 'use strict'; class A { constructor() { } }; A = 1; A:::1 PASS class A {}; var result = A; result PASS 'use strict'; class A {}; var result = A; result PASS eval('var Foo = 10'); Foo:::10 PASS 'use strict'; eval('var Foo = 10'); Foo:::ReferenceError: Can't find variable: Foo PASS eval('class Bar { constructor() {} }; Bar.toString()');:::'class Bar { constructor() {} }' PASS 'use strict'; eval('class Bar { constructor() {} }'); Bar.toString():::ReferenceError: Can't find variable: Bar PASS successfullyParsed TEST COMPLETE