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6 kyu
Typer.js
673 of 887Jim-Y
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Fundamentals
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Objectteam anyone? I'm surprised almost everyone follow the pre-written codes and use an IIFE instead of just creating an object.NaNis a number too. If you wantisNumberto returnfalseinstead, this has to be mentioned somewhere.This comment has been hidden.
for some reason
def self.is_exception?(arg); arg.is_a? Exception; enddidn't work for me. What did work was to traverse the whole tree of classes which descend from Exception and then test the arg's class against that whole list.CoffeeScript initial setup of typer does not match JavaScript version.
NoMethodError is_a? Exception => false , so Many previous solutions is not right. Test cases should be improved.
I don't think is a good kata..
Hi, I am using Ruby and I found the following codes would pass the Test Cases.
def is_number? a; a.is_a? Fixnum; endThe Numeric type includes
Fixnumb, Float, etcso more Test Case shall be added.Ex:
Test.expect Typer.is_number? 5.0This comment has been hidden.
Something strange with tests in this kata. When I do Run Tests everything green, but when I submit it gives me: failed on number literal arg. failed on Number constructor arg. failed on casted to Number arg.
What does it mean, can you decifer? I have no idea how looks test cases I've failed.
Yeah, I get that error too
Only one fail
failed on Number constructor arg.What to do? I can't pass number testing, so frustrated!!!Translation in Ruby added http://www.codewars.com/kata/typer-dot-js/translations
What's the point of testing 4 "different" undefined values. They're indistinguishable for test function.
Maybe those tests are useless, but gives higher coverage, and they doesn't affect the possible solutions anyways. But good points there, thanks. I will review them.
Sorry, I don't understand how four tests can give better coverage comparing to one test. I'm not saying all four to be removed.
I mean, when I was creating the test cases, I wanted to cover every possible cases to generate undefined value, either by passing an explicit undefined, or passing some expressions which will generate undefined implicitly. (or at least cover some of these cases :)) It can be that since every expression will generate the same undefined value, creating 4 tests were needless...
From the tests:
I think this test case is misleading. isNumber should return true for NaN values and this is ok. Since NaN is number (links to the EcmaScript spec: Number type, NaN)
Anyway, this thing about NaN should be mentioned in the description.
HI, i got stuck with this kata. All test i have done are running fine, but when i submit it i get "failed on String constructor arg!" error.. Never used JS before so i am not even sure where to start? Any suggestions would be great.
Thnx
It seems your
.isStringmethod doesn't recognize a string created this way:new String('a new String')ie usingStringas constructor.By the way, there're more than 50 other test cases after this one. This kata is average ranked 6 kyu, if you really never used JS before may be you should try to solve easier ones before.
Thnx for info... any1 suggestions for easier kata?
OP solved it, closing
Needs a better description of the methods to implement.
Modified description. Being more precise on method description would mean a so big hint, that the apprentice wouldn't take any time searching for possible solutions, since everything would already be in the desc.
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Arrays are Objects in Javascript, so:
should return true.
Returning
trueforisObject([])would be misleading, say i want to check ifvar myObj = {prop: 2}is object, then performhasOwnPropertyon it would lead to unexpected errors. Otherwise, I understand your concept, maybe the name isObject is misleading, isPlainObject would be better.Then you're going to have to define "plain object" in some strange way that's not exactly congruent with the Javascript language as it stands. Not that I don't see your point; it's just that if JS doesn't make the distinction, then a base type-checking library shouldn't either.
After all, i'm still not convinced why
isObjectshould return true for[]. Could you please be more specific? Maybe my description was bad to use the word type. I think a functionisArrayshould check if the argument is an array,isObjectshould check if the argument is a JavaScript object, not OOP object. I don't know if you are familiar with jQuery, but according to the reported issue,$.isEmptyObjectshould returntruefor[]since [] is an object, and empty. But its not the case. What do you suggest? Remove isObject method from the kata, or the tests should pass on isObject with an array as argument? That wouldn't make sense imho :(I'd advise simply explaining what you mean by the different "is"es. Other good ones to describe would be things like Boolean and Number; should they include "boxed"
new Boolean(true)or not, that kind of thing.isObjectshould returntruefor[]becausetypeof [] === 'object'. The only thing that should returnfalsewithisObjectis a Number, String, or Undefined (and possibly null). Everything else is an object (even functions technically).I suggest you either scrap
isObject, or descibe in detail whenisObjectshould returntrueorfalse. The problem is that the wordObjectcan mean many different things. Good luck :)Hi, thanks for the suggestions, i updated the description, i hope its more clear now. Please provide more feedback if you have time ;)
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Partly agree. I agree that it is JavaScript which is a dynamic language, it was not designed to work with types. But, this site, and this kata is not intended to be a reference for type checking, it only covers an uncommon case/task in JavaScript. Maybe checking if new String(smtg) is Object or String just doesn't make sense, but we can do this, and i think its worth to make a kata around this issue. There are plenty more katas here what only reflects to one of JS's uncommon features and the warriors can profit from them, not because they are advised to use it in prod, but they will see these cases once in a while. Thats my opinion :)
Btw i did this kata TDD style, i first wrote some ~50 test cases, then made the default "solution".
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See, and that's where I disagree. Javascript is a prototypical language, and as such is heavily reliant on types, it's just that the types are highly mutable. Since this is a fairly basic kata, a lot of people completing it may be learning the language, and I don't think we should be teaching that Strings and Numbers aren't Objects.
Beyond that, since JS doesn't support your typing definitions, your requirements aren't (and can't be) consistent with the language. You say isObject should return true for Object.create(), but Object.create() can create any type of object. For instance:
That's an empty array. Barring re-writing Object.create, There's no way of knowing how the empty array was created, just that it was, and you have it. The current requirements have this case as Schrodinger's array: isObject must return both true (made with Object.create) and false (is an array).
Hmm, you have some point. I really don't want to let this topic go, since this really bothers me, and my mind, but if it is misleading to new learners, then would be happy to delete this kata, than making bad intentions in newcomers. If some more people will vote for a drop, i will drop this.
Question: Are you satisfied with the conventional ways for type checking?
Maybe it just me who are not satisfied enough with the ways we validate input arguments now :) I know, i know, TypeScript, Dart, other transpilers... :)
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I modified the details, i dropped isObject, but also mentioned it :) Thanks for the advices. Also if you have some suggestions for the tests/etc please provide ;)
Your tests look thorough to me. :)