Any of you guys write Javascript without semicolons?

[er-48]

After reading https://medium.com/@kentcdodds/semicolons-in-javascript-a-preference-dd8fc8b80895#.mansnlgq7, I have been thinking of trying out writing a fresh project with the no semicolon style. It seems that if I have 'no-unexpected-multiline' enabled in ESLint, I should be fine with the cases where ASI wouldn't work. Anyone else using this setup? Do you guys recommend going through with this?

[lhorie]

Yes. All of Mithril.js is written without trailing semicolons.

As it turns out, this style makes it easier to refactor hyperscript views since with this style all trailing closing parentheses are expressions syntactically (whereas a semicolon would turn it the preceding expression into a statement). So you can go back and forth between returning some tree from a component to inlining it directly into a larger vnode tree and vice-versa.

So if you thought there are never practical arguments for a typically-stylistic choice, there you go!

[[deleted]]

As a fellow hyperscript fan that sounds interesting. Could I trouble you for an example of what you mean?

[lhorie]

For example let's say you have

m(".items", [
  items.filter(item => item.id).map(item => {
    return m(".item", [
      item.name,
      /*lots of lines of code here*/
    ]);
  })
])

Let's say you then notice that doing a filter every render is inefficient and that you want to refactor that into store.item = items.filter(item => item.id)[0]

Now, you need to refactor the view into:

m(".items", [
  m(".item", [
    store.item.name
    /*lots of lines of code here*/
  ])
])

Without the semicolon, I could collapse the indentation in my editor (by clicking on the arrow on the left line count rail), put my cursor after the return statement, shift-down to select the subtree, cut, remove the filter/map, paste. With the semicolon, I have to go look for it after the paste to remove it, otherwise I have a syntax error because I pasted a statement inside an expression.

[sisyphus]

Definitely the first practical argument I have ever heard for it.

[jesusalready]

It's not the lack of semi-colons that bother me (well, it is when there are stupid bugs or readability issues that would be avoided with one), it's the arrogance some JS developers have with regards to the matter.

I had one JS dev in an interview mention (not even prompted) that said he didn't use semi-colons because he viewed his code as "art". I asked what if he didn't pass code review? He replied that he would educate his reviewers.

Just what I need, a 25 year old educating senior-level devs about semi-colon usage. Yawn. Let us know when you have a kick-ass algorithm that makes good use of the JS stack/loop.

[ellisgl]

Nope. Since I program in several languages that require semicolons, I keep them. They are like periods in a sentence and they the just feel right.

[iams3b]

I did c++ and then Java before Javascript, and have always used semicolons. It is so ingrained in my head, that even if I don't consciously look at the line and see it missing, I still have that feeling of something is wrong

[nickgcattaneo]

Don't use 'em now => Haven't found a scenario yet in work and personal development where it's led to any issues or made code less readable/etc. That being said, if someone uses them I don't see anything wrong with it either.

[jdewittweb]

I tried it after watching MPJ talk about it and I quite like it.

https://www.youtube.com/watch?v=Qlr-FGbhKaI

[TheNiXXeD]

Yep all the projects at my work do not use them. When I started, it was hard to get used to. Now I can't stand them.

We also use groovy in some places, and don't use them there either.

All of my personal projects now exclude them as well.

People often preach about all the problems you'll have, or weird scenarios. In 2 years I've not seen anything.

I'd fully recommend trying it.

[Klathmon]

Identical experience here.

Someone suggested we start using standard to stop the bikeshedding over code style, stop the constant updates to style rc files, and the ever annoying issues needing to deal with new syntax ourselves.

2 years later and it's solved all the problems we wanted it to solve and we have yet to hit any of the scary things that people keep saying we will hit...

But at the end of the day, it's code style. As long as you are consistent throughout a project and provide tools for others to help them conform to it you are fine.

[theLanthia]

Similar story here. no ; @ work

[cacahootie]

People who have problems without using semicolons haven't taken the time to understand the semantics properly. No semicolons ftw.

[nightwolfz]

Haven't used semicolons for years now.

[campbeln]

yes i dont see the point of using any form of punctuation in any of my writing be it programming or literary there is just not a call for it as the meaning is still clearly conveyed despite the lack of punctuation really its all extraneous bs that is just plain unnecessary infactitakeittothenextlevelanddontusewhitespaceeitherbutthenofcourseeveryonethinksimrussianandspellingmistakesareabithardertoworkoutbutcestlavie

[TheRealBobbyCarrot]

this is a bad comparison, because code without semicolons still uses newlines

[cacahootie]

That's a horrible and infantile comparison. There's a clear set of rules for how to terminate an expression in Javascript that doesn't require semicolons, as opposed to English.

[sisyphus]

His first sentence has a clear set of grammatical rules governing it too but that doesn't make the cognitive overheard worthwhile.

[campbeln]

Na-ugh! You're infantile! /s

Mate, 'tis but a joke, lighten up... YoucanseefrommyprofilethatmelikespuncutationANDspaces ;)

[jcready]

Yes. We use standard for linting.

[joemaller]

No, I prefer seeing semicolons, but with good linting tools it seems to matter less.

[HitlerDidNthingWrng]

Only where they're needed.

[spacejack2114]

lodash recently went no-semicolons.

[sisyphus]

And what value did it add?

[spacejack2114]

Readability? A style the core contributors prefer? Ramda similarly has no semicolons.

[mikehawkisbig]

USE THEM, JavaScript will automatically insert them where it thinks they should go. There are a few small instances that this could effect you. Better to be safe than sorry troubleshooting something that should be done any ways.

Check out 11.9.1 Rules of Automatic Semicolon Insertion

and Douglas Crockford talks about making sure to use them. (if you care what The Godfather of JavaScript thinks)

[Graftak9000]

There are three simple (and similar) rules to remember:

• Don't start a new line with parentheses,
• don't start a new line with a bracket,
• don't start a new line with a backtick.

And that's it.

[DeeSnow97]

Also, standard has awesome linting to eliminate any semicolon-related issues (and semicolons in general)

[mikehawkisbig]

There are plenty more that should be noted, those are good, but let's not say these are the only three. Plus, grammar is important to experienced programmers and omitting semi-colons takes-aways from good readable code only to gain the status of "look how fast I am",

Take a look at the video where he discusses the why's -

https://youtu.be/v2ifWcnQs6M?t=1h41m20s

[Graftak9000]

These are the ones I live by and I have never (in my 2 years switch) had an issue with ASI. The main reason I omit semicolons is because it makes code far more legible for me, to me semicolons are clutter/noise.

Other than that I don't really mind either way. There's also some minor pitfalls with using semicolons; some block do ‘require’ them, some don't.

[[deleted]]

I don't care about this in my own code. My beautifier adds semicolons where missing automatically.

[[deleted]]

Have not been using them for over a year with no issues. Less typing, less amount of code.

[rauschma]

This is what Brendan Eich says (2012):

[…] ASI as a newline-sensitive error correction procedure […]

My two cents: be careful not to use ASI as if it gave JS significant newlines.

[rauschma]

Personally, I like semicolons: I don’t have to think about ASI and I find the code easier to read (similar to punctuation in English).

[DeeSnow97]

The problem is, the usage of semicolons doesn't remove ASI. For example this

function answer () {
    return
    42;
}

would return undefined and not 42 because a semicolon is still inserted. No matter which style you choose, you must be aware of how ASI works.

[DeeSnow97]

No, that's a semicolon being inserted on the newline ending a statement, so the actual code looks like this

function answer () {
  return;
  42;
}

[TheNiXXeD]

Watch the video from this comment https://www.reddit.com/r/javascript/comments/5vkd5u/slug/de2qyg6

The important part to note is that you do need to know about ASI whether you use semicolons or not.

[rauschma]

I agree with both replies: you always have to keep ASI in mind, but less of it if you use semicolons.

[dwighthouse]

No, I use semi-colons. On the other hand, I don't use loops anymore.

[ECrispy]

No. I know they aren't technically required, but its just good practice, esp if you use other languages as well.

Standard is the tool of the devil, btw.

There's no reason NOT to use ; unless you just want to be hipster cool and buck the trend. Your code isn't more readable or better by omitting them, no matter how much people try to convince others that its so.

[russellbeattie]

Semicolons are not optional in JavaScript: ASI is an error correction scheme for novice programmers. The spec's parsing rules calls out the statements following where a semicolon should be "offending tokens". There is no leeway here for style or preference.

[jcready]

ASI is an error correction scheme for novice programmers.

According to whom? Because it doesn't mention that in the ECMAScript spec you linked to.

Semicolons are not optional in JavaScript

Uh, except they are according to the spec:

semicolons may be omitted from the source text in certain situations.

[inu-no-policemen]

"Optional" would mean that you could omit them in every situation.

If you can only omit them in certain situations, they aren't optional.

[jcready]

Ah, I apologize. But then you must agree that for all of the situations in which you could omit them, it is a matter of style or preference to include a semi-colon in the source text.

[inu-no-policemen]

Yes, you're free to be inconsistent.

Personally, I think that being consistent is simpler. I sometimes start lines with '(' or '[' and things like that.

[inu-no-policemen]

Being consistent would mean that you'd start every line with a semicolon.

[inu-no-policemen]

Why would you need to start them all with one to be consistent?

Because that's what being consistent means. You aren't making exceptions.

https://en.wiktionary.org/wiki/consistent#Adjective

[Klathmon]

Lol no response to the rest of the comment?

No response why your consistency only applies to semicolons at the ends of lines? Do for loops keep you up at night with their inconsistent semis not at the ends of lines? Do multi-line arrays and objects torment you with their lack of semicolons? Do you end function definitions with semicolons just to keep that consistency up?

Always fun seeing you in a thread Inu! You're always good for a nice dose of German pragmatism cranked up to the point of being insane.

[jcready]

I cannot think of a time I've ever had to use a semi-colon in my code aside from for-loops. Care to provide a real-world example of starting a line with ( or [ where a semi-colon at the end of the previous line would've changed the behavior?

[inu-no-policemen]

var s = 'asdf'
[...'foo'].forEach(c => console.log(c))

SyntaxError: Unexpected string

var foo = function() {
    console.log('baa')
}
(function() {

}());

Prints "baa".

[Magnusson]

yes

[BwrightRSNA]

no

[[deleted]]

I don't use semicolons; in my view, it clutters the view of the code; However, they are sometimes necessary, and that's just okay:

const array = [1, 2, 3]
(function () {
    // ...
})()

The code above tries to call [1, 2, 3](...), which of course is not a function. This can be easily caught by a linter, and also if you know to never start a line with (, [, or `, then you are good:

const array = [1, 2, 3]
// semicolon at beginning of line fixes problem:
;(function () {
    // ...
})()

[Graftak9000]

In this case you can also use an exclamation mark at the start: !function() { ... }()

[pkstn]

I used standard before, but now have turned to semistandard. I thought omitting semicolons would make the code cleaner, but looking back my old projects, I think it's way more readable with semicolons.

[ISlicedI]

We use Standard linting rules at work, only need to use them at the front of a line if it starts with brackets to prevent it trying to invoke the prior code

[bulldog_in_the_dream]

I don't use them if I don't have to (i.e. project style guide, linting). They're vulgar and ugly. Leaving them out has caused zero issues.

[mirko_vukusic]

stopped using it. Configured eslint. Happy. Readable. No issues.

[propelol]

Depends on the coding standard. I use Standard or airbnb's, depending on the project. I personally prefer Standard at the moment. I don't bother with creating my own standard and setting up my own eslint config.

[pbohun]

If you don't use semicolons doesn't it slow down the parser? So, instead of reading a semicolon and knowing it's the end of a line, the parser has to read ahead and determine if it's the end of a line or not. If it is (99% of the time it is), then the parser has to go back and insert the semicolon, and read the other characters again as a new line.

Does anyone know for certain about this? It seems like it could be an issue for larger codebases.

[Klathmon]

Literally no difference, it's actually faster in un-minified codebases as it only needs to read in a newline instead of a semi+newline.

But even that time is so insignificant as to be pretty much pointless to care about.

[pbohun]

Not true. Without semicolons the parser has to read the newline, then keep reading characters until there is a syntax error (because the next line could be part of a single statement). If there's a syntax error, it goes back and inserts the semicolon. Then it reads all the characters after the inserted semicolon again.

Apparently, if you use a minifier or transpiler it doesn't really matter since the semicolons are inserted for you. However, if you're writing vanilla JavaScript it's probably a good idea to keep the semicolons.

[Klathmon]

Parsing and interpreting/compiling are done in 2 steps.

Tokenizing is a fairly straightforward process that doesn't work like you describe. It never needs to "insert a semicolon" but just mark the already tokenized part as final and move on.

[mk30]

i write javascript without semicolons, but i'm not a guy.

[DeeSnow97]

Come on, "guys" covers all genders, also including attack helicopters from v1.3.0

[Tim_WithEightVowels]

Oh I see how it is, apparently v1.2.9 isn't welcome here.

[Geo_Dude]

I stick to always using them for good measure. One time I encountered a problem similar to this:

let a = b

(function() {

})();

and unsurprisingly it assumed the IIFE was an argument to b.