Why I sometimes hate JavaScript

http://geekregator.com/2015-02-27-why_i_sometimes_hate_javascript.html

by mschoebel • 11 years ago

42 62 11 years ago

bceagle• 11 years ago

Sure, this is annoying, but the reality is that this type of stuff is very easily avoided through the use of linters. IMO, you should never work on a dynamic scripted language like JavaScript without constantly running a linter in the background to pick up stuff like this.

oweiler• 11 years ago

Exactly my thoughts. Just ran the snippet through JSHINT and while it doesn't recognize the exact error it shows you the location where it happens.

http://jsfiddle.net/hnxjxyte/

pixelman32• 11 years ago

Plus, with a text editor plugin like https://packagecontrol.io/packages/SublimeLinter-jshint it becomes a no-brainer.

tshadwell• 11 years ago

Honestly, there should have been a loop there. The author introduced un-necessary complexity and a bug appeared. Not that Javascript is a great language.

tinco2• 11 years ago

If you only hate Javascript sometimes, you are definitely new to the language. That said even in a proper language like Ruby this particular bug can happen, that's why communities around these languages strongly encourage proper discipline, enforced by tools.

This bug most definitely should've made your tests go red, your linter give a warning and your code metrics suite should have a thing or two to about the huge expressions and 10+ line function they are in.

mschoebel4• 11 years ago

Thankfully the bug DID make my tests go red.

unwind2• 11 years ago

Is a function longer than 10 lines considered a problem by JavaScript analysis tools (or their users)? Surely you jest?

tinco2• 11 years ago

No, by Ruby analysis tools like Rubocop. For my Javascript I use CoffeeScript, and I rarely go over 10 lines for a function. Javascript obviously is a bit weird in this because many Javascript programmers wrap whole prototypes in closures.

If your function is over 10 lines, it's probably bad, just look at your functions. Every 10+ line function I've ever written was only that long because of laziness and reducing them has always resulted in better legibility.

warfangle• 11 years ago

That's not a function longer than ten lines. That's a single expression longer than ten lines.

savanaly• 11 years ago

Whenever you can't find the bug in javascript, I beg you to run the code through jslint. It would have caught this right away.

garretraziel• 11 years ago

What Node.js taught me is that JavaScript is language like any other. It has good parts, it has quirks and you have to know what are its strenghts and what are its weaknesses to use it properly. And you can say that about any other language.

nothrabannosir4• 11 years ago

Ehm, yes. Sorry to ask this, but what is your point? I don't understand why you are saying this thing, which nobody here would disagree with.

Does what you just said mean that we shouldn't talk about JS's weaknesses?

Or do you mean that we can, but that the points the author brings up have been beaten to death time and time again here on HN and this post + the inevitable comments it will attract have nothing to offer?

Those are the only two options I can think of for now. Or did you mean something else?

nkozyra3• 11 years ago

As I mentioned in another comment, whether this is inherently a weakness is up for debate. Valid code that fails can happen in any language. The problem here is Javascript can be very, very forgiving, which allows one to make mistakes like this.

There are many totally lucid, on-point criticisms of Javascript and at least once a day the language ticks me off, but this one is not so black-and-white.

agumonkey• 11 years ago

New learning philosophy: starts with the corner cases, papercuts and deadends, then enjoy the ride.

falcolas• 11 years ago

Lots of comments here, and on the blog, essentially stating "It's not Javascript, it's that you forgot to [lint|test|format|.+]"

There are tools to make up for these language deficiencies, but our attitude to those bitten by the language deficiencies it's truly unfortunate.

Even Python, everyone's second favorite dead horse for dynamically typed language problems, would throw an error here.

lostcolony2• 11 years ago

Agreed.

"It's not the language's fault; it's your fault for not using all the tools and best practices that make the language tolerable!"

That, to me, sounds like the language has some deficiencies.

jerf• 11 years ago

These two things are not exclusive. The language can be deficient, and you can be irresponsible not for using well-known, long-established tools for addressing those deficiencies.

Normally I'd toss in a jab about deficiencies in choosing your language, too, but Javascript gets a bit of a free pass here on the browser.

nkozyra3• 11 years ago

The real issue here is it's not an error.

In another language the compiler/parser may have thrown a warning, but the issue here is actually that this is valid Javascript. Poorly composed Javascript, but completely valid.

Of course, jslint will complain about it (and a dozen other style things), so the more people utilize tools like that, the better.

More than anything, it's yet another reason to employ unit testing. Valid code that fails is very hard to debug without unit testing.

tomphoolery• 11 years ago

Having JSLint and a test framework in my toolchain when developing with JS is so essential...it's like trying to write Ruby without using unit tests.

nailer• 11 years ago

First thing I did was paste this into an an editor, hit ctrl J, and see if jshint sprang up anything:

      12,40: Expected an assignment or function call and instead saw an expression.

Adding the missing + (and hence removing the expression which doesn't do anything) fixes it.

nkozyra3• 11 years ago

If everything is defined beforehand, jshint will show two warnings. The code is still valid.

The OP is talking about catastrophic errors as a means for surfacing problems in code. That's a pretty old-school (and I don't mean to pick on the OP, he mentions his background in the post) methodology for quality control in code. It worked a lot of the time in compiled languages because they're far more syntactically strict than languages like Javascript.

And that's why we need tools like jslint/jshint. Whether that's a good thing or not depends on your comfort with the language - having the flexibility to structure code differently can be seen as a positive, but you do open yourself up for these types of errors.

vcarl• 11 years ago

This is like the

    if (x = true) {}

kind of error. Yeah it sucks, but it's not really the language's fault.

Not to mention that that large a block of addition is bad code smell to me.

Flimm• 11 years ago

Yes, it is the language's fault. The language could have been better designed, here are some solutions:

1. Assignments in conditions could be required to be surrounded with an additional pair of parentheses, like this: `if ((x = true)) {}`. GCC with warnings already requires this for C.

2. The assignment operator could be something other than the equal signs, for example, it could be `:=`. Assignment is so different from mathematical equality and beginners to programming trip up on this all the time, it's a shame programming languages copy each other for familiarity and keep this bad design.

3. Assignments in conditions could be banned out right, like Python does.

macspoofing• 11 years ago

Yeah it sucks, but it's not really the language's fault.

Imagine a language were assignments were only done via := and comparisons with = or ==. A programmer would never encounter this error.

dukky• 11 years ago

I really don't see why this isn't a syntax error

What is actually being done with the calls after the chain of +'s?

Edit: Something to do with semicolons being optional in js?

afandian• 11 years ago

This is valid JS:

    1;
    2;
    alert("returns undefined");
    confirm("return true or false?")
    (function() {return 3})();
    (function() {})();

What's being done with the values of 1, 2, undefined, true/false, 3 and undefined? Nothing if they're not assigned. But as every function returns a value and invocations are therefore an expression, it would be impossible to disallow expressions to be evaluated but not assigned.

d4n34• 11 years ago

Javascript has "semicolon insertion".

It tries to parse a newline with no semicolon as continuing the current expression, if it can't, it inserts a semicolon.

It's a 'feature' that's caused too many bugs and is a warning in most linters.

d4n34• 11 years ago

Jshint catches this with 2 warnings: missing semicolon and expected assingment or function call.

In Sublime text 3, you can have inline warnings and as-you-type linting with the sublimelinter jshint plugin:

https://github.com/SublimeLinter/SublimeLinter-jshint

taytus• 11 years ago

I saw the error in 30 secs. Advice: try to use dislike instead of Hate.

david-given3• 11 years ago

Optional semicolons is my biggest hate with Javascript --- combined with expression statements silently discarding their result, it makes this kind of mistake far too easy to make.

Personally I've never understood with Javascript strict mode doesn't make semicolons mandatory.

nothrabannosir4• 11 years ago

Isn't strict mode purely semantical? IIRC you can implement a use strict pass purely on the AST, after the parser.

It's not an excuse, of course.

david-given3• 11 years ago

Bah. You're absolutely right, of course, that's why strict mode won't help.

Now I find myself wishing there was a stricter mode. <script type="text/sensible-javascript">, perhaps...

shaunrussell• 11 years ago

JSHint is a thing.

Also, I think you are looking for typescript.

axeldelmas• 11 years ago

You'd spot that right away if you had a visual jshint/jslint plugin in your IDE. It's a real time saver to have one: there are dozens of cases like your example that are valid JS, although it's not what you intended to write.

nothrabannosir4• 11 years ago

The "JSlint catches this" argument is valid, but not to defend JS. When you say: "with a linter this doesn't happen," you're defending (Javascript + linter), not Javascript.

Just as when someone says: Typescript would not allow this, or that. Or use strict mode would not allow that. Yes! True. They would not. But they are not JS: they are Typescript, or JS strict mode, or...

There was an article here a while back about "tabooing your words"[0], and I think it applies very well here. Instead of talking about just "Javascript", let's try to not mention it. Say "Ecmascript 5 without any tooling," or "ES 6 with 6to5", or "Ecmascript 5 with a linter", or "Ecmascript 5 in strict mode with a linter."

Suddenly, you will find that everyone in this thread agrees: "Ecmascript 5 in non-strict mode, without special tooling" is a shitty language for humans to write because mistakes so easily go unnoticed. And humans make mistakes.

And if you do use linting, or whatever, no need to feel offended: we're not talking about that language!

In essence, saying "the linter would have caught this" is like saying "Typescript doesn't allow that". It's completely true, but it's a different language.

The author was not talking about "Javscript", but about "Ecmascript 5 in strict mode without tooling." And I think we can all agree: that language is problematic.

[0] https://news.ycombinator.com/item?id=6855568

EDIT: Author was talking about strict mode. Still problematic.

mschoebel4• 11 years ago

Or use strict mode would not allow that.

It was in strict mode. It allows that.

nothrabannosir4• 11 years ago

True, bad example. I was talking in general: the "yes, X has this problem, but if you tweak it to be X', then it doesn't." argument. You're not talking about X but X'.

But you're totally right, use strict is not syntactical. (I think?)

d4n34• 11 years ago

It's way better to use [values].join('') here... It's probably faster and it coerces all values to string.

If the first couple of results were numbers or booleans, they would be summed:

    > true + 10 + " result"
    11 result

    > [true,10," result"].join('')
    true10 result

mschoebel4• 11 years ago

All the functions in that code return numbers.

d4n34• 11 years ago

Ah ok. At first glance it looked like he was putting together something like an url.

alexsop2• 11 years ago

Making [`.reduce`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...) a significantly better choice.

thebouv2• 11 years ago

Good programmer, bad programmer. Good code, bad code. Let's not all pretend we don't have stupid bugs in our code regardless of editor, linting or language.

JS is a mediocre language. It is popular because it is ubiquitous, not because it is good. It really does have bad error handling, weird optional rules, problems determining type when adding/concatenating with +, and the list goes on.

His was a syntax error that could have been caught with linting, sure. But there is plenty of well-formed JS that passes linting but still behaves badly due to the language itself.

Mithaldu3• 11 years ago

Specifically the mistake Javascript is making here is one designed into the language itself:

When there are no semicolons between statements, it will automatically and silently insert them. Without this behavior his mistake would've been a compile-time error and easily caught. (Of course, this leads to the bigger bug that sometimes Javascript will insert them in the wrong place.)

He doesn't know exactly what the bug in Javascript is and how to point it out accurately, but he is absolutely correct that there is a bug in Javascript's design.

ttty2• 11 years ago

JS is a mediocre language. It is popular because it is ubiquitous, not because it is good.

JS is a popular because runs on browser by default.

thebouv2• 11 years ago

Yes, which is why it is so ubiquitous.

TheOtherHobbes2• 11 years ago

As someone pointed out, the implied semicolon isn't the problem.

The problem is that the code is written in a way that makes it vulnerable to an implied semicolon.

The core syntax of JavaScript won't be changing any time soon, so it's important to teach beginners how to write code that minimises mistakes like these.

I haven't seen many books and tutorials attempt this. So it's unfair to blame beginners when there's so little encouragement to learn a strong defensive coding style.

jshint is nice for basic sanity checks, but it can't deal with bigger structural or stylistic mistakes. You can only fix those by learning from strong examples of good, clean code.

I think this applies to all languages. Being able to solve a problem and write a solution in code symbols isn't enough. I wonder if it would help everyone if there was a store of established best practices with examples for every language.

Mithaldu3• 11 years ago

You know that kind of bullying where someone grabs someone else's arm and uses it to hit them in the head with their own hand, while yelling "Stop hitting yourself! Why are you hitting yourself?"?

Javascript's automagic semicolon is that, and you're the kind of person who condones it.

Yes, at the end of the day one has to learn how to deal with the automagic semicolon, if one doesn't just give up on Javascript wholesale and finds a way to write better languages. However the very presence and behavior of that code in every javascript interpreter is still a cruel misbehavior whose implementation was a mistake. It is just as cruel and as much of a mistake to imply even in the slightest way that it isn't.

The correct response is to not blame the coder who stumbles over that, but to gently let them know that yes, Javascript is a bad language, and to gracefully show them how to not fall into that trap.

emehrkay• 11 years ago

My approach, in any language, would be to collect it in an array and sum (or concatenate) it at once.

    var values = [];
    values.push(phraseValue( result, queryData ));
    ...
    var value = values.reduce(function(prev, next) { return pre + next; });

I understand that COLLECTION.reduce may not be in all javascript implementations (or even in all languages), but that would be my first thought on how to handle that mess. Id probably even make it a function addAllOfTheseValues(result, queryData);

I also dislike direct string concatenation, I always try to use print type functions because it is easier to separate variables from text and spot potential errors. I'm happy that JS is getting this.

tempodox• 11 years ago

That title looks rather backwards to me. You don't need a reason to hate JS. You do need a reason to not hate it.

QuantumRoar• 11 years ago

I think this is a general problem for people used to the comfort of compiled languages. I also struggle with languages like JavaScript. I always have the feeling that I'm actually doing something wrong or non-standard but the webbrowser is smart enough to understand it anyway.

This feels to me like I'm constantly operating in some kind of gray area where everything is "correct enough". But as others have already pointed out, this can be ameliorated by using the right tools. So the problem is actually purely about taste, I guess.

ttty2• 11 years ago

I've spotted the error in less than 5 seconds... + I personally don't like the way you write code.

collyw• 11 years ago

Doesn't JS have a join function?

I realize that problems like this are the reason that my coding is going in a more functional direction (I would still say I write imperative code), but I avoid "doing things manually" like this, as its easy to overlook such errors.

bpg_92• 11 years ago

I agree that JSlint would catch this, but then againg that doesn't seem like a valid argument to defend JS in this specific subject.

thaumaturgy• 11 years ago

I had a similar-ish problem just last night. Spent over an hour crawling through some code trying to figure out why it wasn't working like it was supposed to. I ended up doing the divide-and-conquer approach with "console debugging". I was cursing wildly by the end of it.

All to find in the end that I had used ( ) instead of [ ] (or maybe it was the other way 'round?) in a thick spot of code, and Javascript was happy to try to do that without throwing any kind of error.

That sort of thing happens in all languages to some extent, but debugging in Javascript is unmitigated hell.

Why I sometimes hate JavaScript

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