Test 47: About Reflection (topics/about_reflection.js): hasOwnProperty

Question

Test 47: About Reflection (topics/about_reflection.js): hasOwnProperty

davidmatas opened this issue 13 years ago · 5 comments

Hi!

I have a problem with first part of test 47. The solution of ok(keys.equalTo(['__', '__', '__']), 'what are the properties of the array?'); should not be ['0', '1']? Why three elements in the array?

Thanks

Answer 1 · 2012-04-11T22:50:33.000Z

The for... in statement enumerates the 'equalTo' property from the array's prototype. That is the third element. The next example shows the use of hasOwnProperty to restrict for... in to the non-prototype properties.

Answer 2 · 2012-04-12T07:25:55.000Z

mmm, sorry I don't understand it. If I run the example, keys will be an array with only two elements ['0', '1']. Exactly like the next example.

http://jsfiddle.net/jBNWb/

Answer 3 · 2012-04-12T11:18:07.000Z

The code in the koans is actually http://jsfiddle.net/MgVnK/

However, I agree that this example is not sufficiently clear. I will improve it when I get some time. Thanks for reporting.

Answer 4 · 2012-04-12T16:45:53.000Z

@davidmatas I had the same issue - here's my SO question which got some answers that sufficiently explained it for me: http://stackoverflow.com/questions/9322459/having-trouble-understanding-a-reflection-test-in-javascript-koans

Answer 5 · 2012-04-15T22:28:04.000Z

I'm going to update this topic with tests based on:

http://jsfiddle.net/KJCUb/