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isExtensionOf
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| // is A an extension of B ? | |
| // ex: | |
| // class C extends Oject {} | |
| // class B extends C {} | |
| // class A extends B {} | |
| // isExtension(A, B) === true | |
| // isExtension(A, C) === true | |
| // isExtension(A, Object) === true | |
| // isExtension(B, A) === false | |
| function isExtensionOf(A, B) { | |
| if(A === B) { | |
| return true; | |
| } | |
| if(typeof A !== 'function') { | |
| return false; | |
| } | |
| if(typeof B !== 'function') { | |
| return A.__proto__ === B; | |
| } | |
| return isExtensionOf(A.__proto__, B); | |
| } |
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Won't this line always return false?