| function shouldBe(actual, expected) { | |
| if (actual !== expected) | |
| throw new Error('bad value: ' + actual); | |
| } | |
| var error = null; | |
| try { | |
| var charAt = String.prototype.charAt; | |
| charAt(); | |
| } catch (e) { | |
| error = e; | |
| } | |
| shouldBe(String(error), `TypeError: Type error`); | |
| function refer() { charAt; } |