Should String.prototype.split accept variable arguments optionally?

Rick Waldron waldron.rick at
Wed Oct 16 13:46:30 PDT 2013

On Wed, Oct 16, 2013 at 4:25 PM, Benjamin (Inglor) Gruenbaum <
inglor at> wrote:

> On Wed, Oct 16, 2013 at 9:03 PM, Andrea Giammarchi <
> andrea.giammarchi at> wrote:
> > How could change 12+ years of legacy be considered inexpensive ?
> This proposal does not break anything, the only thing that will/might work
> differently is people passing an array to .split right now and expecting
> something like splitting on `firstElem,secondElem...`. Current usages of
> .`split` with a string or with a regular expression will continue to
> function exactly the same, the only thing happening here is adding an
> overload for an array.
> > Non "highly trained professionals" should be simple things or try to
> learn something new that won't hurt... so please make it simpler"
> If we can make life the easier without breaking anything, why not? A lot
> of people use JavaScript on the web in practice for making websites
> dynamic, most of those people are not me and certainly not you but they're
> still probably the majority. How many so called ""jQuery programmers"" are
> there?

As one of jQuery's own representatives to Ecma/TC39, I still stand by my
original response. After reading through those links, I agree with Andrea:
it's a handful of people that just need time and motivation to learn.

> I'm not sure taking a common use case like `.split` on multiple delimiters
> and removing a skill (Regular Expressions) they had to know before in order
> to write code they understand and by that making the language more
> accessible to them is not a good idea.
> There are and have been such API changes in the language. Why have
> `str.contains` if you can just do `~str.indexOf`. Why have `.startsWith`,
> or `.indexOf` on arrays?
> I'm not saying we _should_ add a `.split` third overload in addition to
> the already existing two. I do however think it is an interesting idea that
> in practice a lot of developers, especially ones who do not remember the
> abstract comparison algorithm by heart can possibly benefit from.
> Are you against changes like `.contains` or `.startsWith` too? What do you
> think is the criterea for such additions to the language?

I'm all for new additions, but nothing is free and changing an existing
thing is potentially even more expensive. Brendan's response is the most


> On Wed, Oct 16, 2013 at 9:21 PM, Brendan Eich <brendan at> wrote:
> > It's hard to add extra optional arguments to a long-standing built-in.
> People write code that passes an extra arg that has been ignored till the
> change; browsers that try shipping the new version then break that content,
> user blames browser (rightly so) but also the page, sometimes (not right).
> Agreed. Even without compatibility issues, I get confused questions from
> students regarding the behavior of methods changing behavior based on
> number of arguments (`Array` for example) way more often than I'd expect.
> (and props on the spec, being able to send students there in such cases is
> extremely enabling imo and a great exercise on its own).

Too late to change Array arg handling. In the future, tell students to
construct new Arrays of numbers (that may have 1 entry) with Array.of():

Array.of(42).length === 1;

(vs. Array(42).length === 42; )

> What about the version with the overload accepting an Array instead? It
> seems more backwards compatible than the varargs version.

What version is that?

> Regexps suck away oxygen too, as others note. My suggestion is to focus
>> fire for greater effect. If we need a new variable-split, we want a new API.
> I actually like the existing API for the most part and just wish it made
> life easier at times. Especially for learners. I'd like to teach my nephew
> JavaScript as a first language and I don't want to go anywhere near regular
> expressions.

Again, this is too subjective.

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