Benchmark: Regex match() array vs matchAll() iterator

Script Preparation code:

var re = /\w+/g
var text = `Miss Brooke had that kind of beauty which seems to be thrown into
relief by poor dress. Her hand and wrist were so finely formed that she
could wear sleeves not less bare of style than those in which the
Blessed Virgin appeared to Italian painters; and her profile as well as
her stature and bearing seemed to gain the more dignity from her plain
garments, which by the side of provincial fashion gave her the
impressiveness of a fine quotation from the Bible,—or from one of our
elder poets,—in a paragraph of to-day’s newspaper. She was usually
spoken of as being remarkably clever, but with the addition that her
sister Celia had more common-sense. Nevertheless, Celia wore scarcely
more trimmings; and it was only to close observers that her dress
differed from her sister’s, and had a shade of coquetry in its
arrangements; for Miss Brooke’s plain dressing was due to mixed
conditions, in most of which her sister shared. The pride of being
ladies had something to do with it: the Brooke connections, though not
exactly aristocratic, were unquestionably “good:” if you inquired
backward for a generation or two, you would not find any yard-measuring
or parcel-tying forefathers—anything lower than an admiral or a
clergyman; and there was even an ancestor discernible as a Puritan
gentleman who served under Cromwell, but afterwards conformed, and
managed to come out of all political troubles as the proprietor of a
respectable family estate. Young women of such birth, living in a quiet
country-house, and attending a village church hardly larger than a
parlor, naturally regarded frippery as the ambition of a huckster’s
daughter. Then there was well-bred economy, which in those days made
show in dress the first item to be deducted from, when any margin was
required for expenses more distinctive of rank. Such reasons would have
been enough to account for plain dress, quite apart from religious
feeling; but in Miss Brooke’s case, religion alone would have
determined it; and Celia mildly acquiesced in all her sister’s
sentiments, only infusing them with that common-sense which is able to
accept momentous doctrines without any eccentric agitation. Dorothea
knew many passages of Pascal’s Pensees and of Jeremy Taylor by heart;
and to her the destinies of mankind, seen by the light of Christianity,
made the solicitudes of feminine fashion appear an occupation for
Bedlam. She could not reconcile the anxieties of a spiritual life
involving eternal consequences, with a keen interest in gimp and
artificial protrusions of drapery. Her mind was theoretic, and yearned
by its nature after some lofty conception of the world which might
frankly include the parish of Tipton and her own rule of conduct there;
she was enamoured of intensity and greatness, and rash in embracing
whatever seemed to her to have those aspects; likely to seek martyrdom,
to make retractations, and then to incur martyrdom after all in a
quarter where she had not sought it. Certainly such elements in the
character of a marriageable girl tended to interfere with her lot, and
hinder it from being decided according to custom, by good looks,
vanity, and merely canine affection. With all this, she, the elder of
the sisters, was not yet twenty, and they had both been educated, since
they were about twelve years old and had lost their parents, on plans
at once narrow and promiscuous, first in an English family and
afterwards in a Swiss family at Lausanne, their bachelor uncle and
guardian trying in this way to remedy the disadvantages of their
orphaned condition.`

Tests:

match
(text.match(re) || []).length
matchAll
[...text.matchAll(re)].length

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
match
matchAll

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript benchmarks and explore what's being tested on this particular benchmark.

**Benchmark Definition**

The benchmark defines two test cases: `match` and `matchAll`. These tests are designed to measure the performance of regular expression matching in JavaScript.

**Test Case 1: match**

This test case uses a regular expression (`re`) to search for matches in a large text string. The regex pattern is `/\\w+/g`, which matches one or more word characters (letters, numbers, and underscores) globally in the text.

The benchmark definition is: `(text.match(re) || []).length`

In other words, this test case measures how many times the `match` method can find a match for the regex pattern in the text string. If no match is found, it returns an empty array (`[]`), which has a length of 0.

**Test Case 2: matchAll**

This test case is similar to the previous one, but instead of using the `match` method, it uses the `matchAll` method to search for all matches of the regex pattern in the text string. The benchmark definition is:

`([...text.matchAll(re)].length)`

In this case, the `matchAll` method returns an iterator that yields arrays containing all matches of the regex pattern in the text.

**Options Compared**

The two test cases are comparing the performance of two different approaches to regular expression matching:

1. `match`: This approach uses a single call to the `match` method to search for a single match.
2. `matchAll`: This approach uses an iterator to find all matches of the regex pattern in the text.

**Pros and Cons**

Here are some pros and cons of each approach:

* `match`:
	+ Pros: Simple, efficient, and easy to understand.
	+ Cons: Only finds a single match, which might not be what the user wants if there are multiple matches.
* `matchAll`:
	+ Pros: Finds all matches, which can be useful if you need to process each match individually.
	+ Cons: Requires an iterator, which can be slower and more complex than a simple `match` call.

**Library and Purpose**

The regex library being used is built-in to JavaScript. The `match` and `matchAll` methods are part of the String prototype, making it easy to use regular expressions in string concatenation and matching.

**Other Considerations**

When using regular expressions, keep in mind that:

* RegEx can be slow if they're too complex or contain many repeating patterns.
* Using global flags (`g`) can improve performance by reducing the number of iterations needed to find all matches.
* Be mindful of performance when using regex with very large strings.

**Alternatives**

If you need to perform regular expression matching, you might consider alternative approaches:

1. Use a dedicated library like `regex` or `rsexp`.
2. Write custom code to use the underlying regex engine.
3. Consider using other string processing algorithms that don't rely on regular expressions (e.g., string iteration, loop-based search).

I hope this explanation helps you understand what's being tested in this benchmark!

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Firefox/102.0

Browser/OS: Firefox 102 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
match	43464.6 Ops/sec
matchAll	30287.3 Ops/sec

Related benchmarks:

Regex match() array vs matchAll() iterator (version: 0)

Comparing performance of: match vs matchAll

Created: one year ago by: Guest

Jump to the latest result

match

matchAll

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):