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Comment by duxup | Hacker News Reader

I know at one point w3schools.com was a bit out of date but they seemed to update it.

As someone who has changed careers and moved into web development I found w3schools.com did a nice job of complementing MDN as if I was unfamiliar with the concept (or just forgot entirely) w3 was a good "layman's terms" stop just to start. And if I needed a more technical / granular detail, MDN.

I really wouldn't want to use one without the other.

Many years ago I took some C programming classes in college. It was in the early days of the internet and it was very much a "here's the book, a bit of lecture, now sit alone at your computer and do it". MDN can feel that way at times where it's example is ultra specific and while nothing is technically wrong.... it's like learning a language with a dictionary. w3schools.com fills that gap nicely.

At the same time if I need the dictionary to figure out more precisely how something works and all my options, it's MDN all the way.

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W3Schools also used to be quite bad and misleading; this is an old page with a huge list of problems with W3Schools:

https://web.archive.org/web/20110117085131/http://w3fools.co...

Used to is the important word here. They improved a lot.

I like them. MDN is great, but w3schools is better in giving examples on how to use stuff.

I would rather use a site which started with correct documentation and added examples over time, than use a site which started full of bad documentation and examples, and slowly got corrections over time.

If you use the site after it got corrected the difference is nil :)

I never use W3Schools but I have to say that I sort of feel bad about that because as a policy thing perhaps one should use something that has improved on bad behavior to become good in order to reward the improvement.

Of course improvement without expectation of reward shows a higher moral stature, but it is a stature that is perhaps not to be expected, whereas improvement based on reward seems more likely to exist in our world - given studies of the matter.

EDIT: It seems that Python lists are in fact arrays. Cool, so Python does in fact support arrays. Seems a pretty important fact to point out on a page called "Python Arrays".

Original comment:

There is still some complete nonsense on w3schools. For example, I wanted to know recently whether Python supports arrays. The first result on Google is this page: https://www.w3schools.com/python/python_arrays.asp

There is a small disclaimer at the top stating: "Note: Python does not have built-in support for Arrays, but Python Lists can be used instead."

Why the fuck is your page called "Python Arrays" if you don't plan to talk about arrays?

Then the rest of the page talks about lists, while erroneously calling them arrays, in complete defiance of the disclaimer. I imagine what happened is that someone who doesn't know what an array is wrote the page originally, then someone else came by later and realized it was wrong, but instead of actually fixing it, slapped that half-assed disclaimer on top.

I still don't know whether stock Python actually supports arrays. I ended up just importing Numpy.

Python lists do the job of an array probably for 99% of cases. Depends on your exact definition of an array and if that even matters

The subway does the job of a car in 99% of cases. Doesn't mean they're the same thing. I also wouldn't appreciate an article about subways with the title "Cars".

I have literally never seen or heard of a definition of array according to which lists are arrays -- can you cite one?

Can you cite a common definition of “array” other than a bare minimum of being randomly accessible? (Nothing else is pinned down. Fixed vs variable length, single vs mixed type, or even underlying data structure (cf NSArray)).

By the only universal definition I can think of, python lists are arrays.

Python lists most certainly meet the mathematical definition of array (ie name by index)

It seems you're right. Python lists are arrays -- I didn't know that.

That makes my point even stronger. The article about "Python Arrays" directly claims that Python Arrays don't exist, which is apparently wrong!

The whole point is that I came away from the article believing information that is false.

Arrays are commonly an implementation, while lists are the mathematical or logical structure.

Same as how a hashtable is used to implement a mapping.

As always, as you say, it depends on your definition.

One of the useful definitions of an array is that it guarantees contiguous storage in memory. In Python, there is no way to guarantee that; even if a list is a C array of Python references under the hood, there's no way to store the information represented by those references contiguously in memory. From that perspective, pure Python doesn't have any arrays at all, which is precisely why the popular NumPy has to offer explicit support for numeric arrays.

From another perspective, arrays are a set of O() guarantees for various operations. From that perspective, Python lists will generally meet the specifications that you'd write for a resizable array, or perhaps what you might call "vector", depending. CPython comes with some awful constant factors but the O() of the lists will be what you'd expect.

Rather than arguing about whether Python has "arrays" interminably, it's better to carefully define array, then dispassionately examine Python lists to see if they match that definiton. You'll get a yes sometimes and no others. I say "dispassionately" because too many people seem to assign moral qualities to whether or not something conforms to a given definition, but that's not a path to understanding. No matter what definition you write down for "array", not a single characteristic of Python will change.

"Array" is a pretty loosely defined term that varies from language to language. Python lists are what you may know as "variable-length arrays" of python objects (in other words: not type constrained). If you want type-constrained arrays, you'll use the array module: https://docs.python.org/3/library/array.html

that w3schools page is indeed nonsense. They should probably stick to JS.

Python lists may well be implemented as arrays. I don't know if they are or not, as I haven't read the Python interpreter source code.

If they are, then the article is even worse, as the disclaimer that Python doesn't have arrays is a lie!

Everything in Python is implemented as a dict behind the scenes, which is implemented in C with a few different types. Python does have arrays in the standard library's array module, so yes saying python doesn't have arrays would be a lie.

It depends on how strictly one defines "array." If you mean it generically as "an indexable contiguous memory buffer containing the actual data being indexed," pretty sure Python lists don't comply even at a mechanical level.

While the Python 3 docs for arrays certainly do lean on the type-constraint, I notice it also has the various operations that imply a contiguous buffer (cast to bytes, etc.), so I wonder if that's not the real distinction and the type constraint serves that.

Traditional Python lists are much closer to what I know as a vector: indexable like an array, but dynamically expandable and usually implemented as a list of references to data structures instead of containing the data itself so allows for heterogenous data.

Informally, I've certainly called both types of things arrays, right or wrong, and rarely call anything a vector other than container classes by that name, but I do suspect that's what your parent comment is drilling on.

* Then there's the JS Array class, which acts more like a vector than array by those definitions, so who knows.

I'd be angry at python there. It's python that uses lists like arrays in the standard language, making beginners search for arrays when python would use a list.

That's a pattern of the language and why I don't like it: It's very often almost like the other C-like languages, only to be that much different that it gets confusing. To just ignore that and call a list an array is not correct, but it makes the beginner searching how to do array-like stuff in python succeed in his task.

I'd be more annoyed at that page if they didn't explain the situation, but they do.

> I'd be more annoyed at that page if they didn't explain the situation, but they do.

Actually, they don't. The article claims that arrays don't exist, but you can use lists instead.

Apparently the polar opposite is true: lists don't exist, but you can use arrays instead! (And they're called "lists" for whatever reason).

This is silly. Both "list" and "array" are so broadly defined that they largely overlap.

Then why doesn’t the article point out what definitions it’s using, rather than claiming arrays don’t exist and then talking about arrays?

Python has something it calls lists. Those lists are basically like what other languages would call arrays.

But python also has an array module you can use after an import, it's not loaded by default. That data structure behaves even more like the thing C calls an array.

I don't see why a python list is not a list per se. Don't be confused by the others explaining it is not a linked list - something does not have to be a linked list to be a list. It's still a numbered collection of stuff that can be sorted, thus a list.

Though it is true that as a programmer you probably are first confronted with a data structure called list when you learn a LISP, and that data structure will be a linked list.

Confronting beginners with all this is not useful for them, w3schools just adding a note and calling the python default collection thing an array is thus not that unreasonable. Though I'd prefer it if they just called it a list in the explanation below the note, after explaining that this list structure is what you are probably searching, with a link "look there for what python calls an array". So in that way I agree with you, this is not optimal.

Python lists are dynamic arrays, not linked lists.

Then why does the article incorrectly claim that Python doesn't support arrays?

The whole point of my comment is that I went away from the article still not knowing whether Python has arrays, or not. I can't understand how anyone would defend an article called "X" that doesn't even properly inform you whether X exists

The article is not even wrong. That first yellow highlight is … ugh.

If a programmer from another language asks for an array, I'm going to point them at the `list` class in Python.

As some other sub-comments under your original post note, some uses of an array want the actual data to be contiguous. But Python `list`'s values are references to other values, not the direct values themselves. If you're familiar w/ C, it's closer to an array of pointers to objects. That matters for some niche cases. But in basic tutorial? No. And Python has some built-in types to account for some of the niche cases. Sure, that pointer is not free, and the overhead of a Python object is not free, but Python is a high level scripting language, and generally, `list` provides a random-access ordered collection, which is what most people want when they say "array", and the overhead doesn't matter for many things.

Python's list type is implemented as a dynamic array in CPython. This is not required.

An optimizing Python doing escape analysis could see a list was going to be converted to a set and swap in a set and change the method calls. Or it could see a large number of concatenations and use a linked list as an intermediate form.

I tried adding better examples for "alert"s for example, but my PR got not approved because it didn't fit the exact structure of how the wiki is structured. So they make it intentionally worse than w3schools :)

https://github.com/mdn/interactive-examples/pull/1266

<h1>how to use alert()</h1>

<p>see the Console API</p>

<footer>don't use alert(), don't talk about alert(), don't teach alert(), it's not 1997 anymore</footer>

alert() is very handy to learn, as it gives the new commer something tangible and familiar to use for tests.

You just have to give proper context.

> proper context.

That's not 'tests' — tests would be something like Mocha, or Jasmine — what you're actually talking about here is one of the many forms of ad hoc in-browser debugging.

Automatic tests are not the only way to test software, nor are they sufficient. Whether some software can actually be used is not something that's completely formalizable and so you can't test it automatically. You always need a human in the loop in the end, and alert is a legitimate tool to effortlessly display some additional information on internal state during an interactive user test.

> ad hoc in-browser debugging

Ah, if only there was a single word - a verb perhaps - that developers could use to colloquially refer to this process!

Not testing the code, fidling with the stuff they are learning.

No, the console API is a handy thing to learn. Alert is not handy, it's an ancient function that (a) blocks your page thread, (b) can't show anything except `.valueOf`, (c) can't be selectively ignored, (d) it's an obsolete API from way back when javascript 1.5 was hot stuff.

If you're teaching, teach people to use console.log because that's where they're going to get REAL insight into what the code's doing (console.table you say? amazing!) and never look back. And if you're learning, demand people teach you modern practices. Not ridiculous things from 20 years ago.

It's a little like GoDaddy, or Facebook.

W3schools were so bad, essentially just a click farm promoting any old crap for the pageview, that it'll take a huge amount of correcting, improving, and newly found ethical standards to let me forgive them. Or forget there really was a need for w3fools. They always gave lots of examples, and they were often simply wrong.

Even when they apparently have the answer, until I can validate it on SO or some other place, I'll tend to not trusting...

W3Fools has updated their stance:

"Today, W3Schools has largely resolved these issues and addressed the majority of the undersigned developers' concerns. For many beginners, W3Schools has structured tutorials and playgrounds that offer a decent learning experience. Do keep in mind: a more complete education will certainly include MDN and other reputable resources."

https://www.w3fools.com/

That webpage is why i stopped using w3schools back in college.v nostalgic

I find w3schools dumbs it down a bit too much in certain cases and sort of gets in the way of finding the info you want.

Compare https://www.w3schools.com/jsref/jsref_substring.asp with https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

The MDN doc allows you to run the code there and then - no jumping around to a "Try it yourself" page. Also, MDN gets to the syntax quickly - with w3schools, I have to search for the syntax in amongst a bunch of other junk that I really don't care about at that moment (like browser compatibility).

To a seasoned dev, MDN feels clear, w3s feels like a confusing mess. Maybe for early stage devs it's the other way round?

Both of them seem to be equally useful to me. Both show the one thing I search the most at the top: The example.

In w3schools, "Definition and Usage" starts referring to "start" and "end" parameters before even mentioning them. It's really quite annoying to read that first and then see the syntax...

As someone who is new to all of this, I like W3 schools as a complement as well. I like the MDN but a lot of it goes over my head. W3schools does a good job of breaking some stuff down and can be easier to read. But at the same time I find the MDN much more resourceful when I'm trying to get down to the nitty-gritty.

Yeah I certainly flow from one to the other a lot.

If I need the finer details and understand what i'm looking up, straight to MDN.

If I'm in over my head and want a bit more context, back up to w3.

And then sometimes back to MDN ;)

I feel the need to "me too" here. I use MDN almost exclusively now, but W3 schools helped me a TON before I could understand MDN.

I am of the opposite experience. I find the w3schools site to be so terribly out of date, with such terrible approach to learning and documentation I found it did me more harm than good.

If you actually read the docs on MDN, you can write stuff that actually work instead of copying random snippets of code until it does what you want to do.

Part of w3schools' bad reputation comes from intentionally failing to disavow itself from the W3C (w3.org) while providing commercial certifications. The W3C asked them to clarify this non-affiliation several times and it seems the only thing that ever came from it is one sentence on the About page.

Seeing that many developers (including experienced professionals) thought the two entities were related, it seems obvious that they directly benefited from that confusion. Luckily this seems less relevant now that WHAT WG exists separately from W3C and ECMA/TC39 is more prominent.

I didn't know that thanks.

I wonder how many folks using w3schools.com really know who w3.org really is ;)

Part of w3fools bad reputation stems from the fact the site is (or at least was) full of errors - especially their SQL part.

W3Schools has been turning-up in my web searches for probably as long as it has existed [1] and I can't remember it ever occurring to me that it was affiliated with the w3c. Maybe this really was a concern to w3c but I seriously doubt many other people were mislead.

[1] Just checked. Twenty years!

I've been doing web dev work for over a decade now and always thought there was an affiliation with their w3schools and W3C. Fortunately I've only used them as a quick reference and not for any kind certification as OP mentioned they also provide.

TIL

I never did because I had seen sketchy brands trying to mimic popular brands before, so I was primed to be skeptical.

But it is pretty natural in how language works for people to see similar names and assume an association. And you can't reconsider an unconscious association, since it's unconcious.

it had such good SEO precisely because it was mistakenly assumed to be run by w3c by a LOT of devs who proceeded to click those links enough as to inform google that this is a "important site"

I stayed away from W3schools for a long time because the bad reputation, but I started to use it again recently and noticed that it had imropeved greatly.

W3schools is better when it comes to HTML+CSS with JS sprinkled on top questions IMHO.

MDN for the specifics.

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