Benchmark: matches exec - MeasureThat.net

Tests:

matches
"``` java a b c".match("^...\\s*(\\S*)")
exec
new RegExp("^...\\s*(\\S*)").exec("``` java a b c")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
matches
exec

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36

Browser/OS: Chrome 114 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
matches	9805494.0 Ops/sec
exec	8075230.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's happening in this benchmark and explain the different approaches used.

**Benchmark Definition**

The benchmark is defined using a JSON object that contains metadata about the test, such as its name, description, and script preparation code. In this case, both fields are empty, which means the script itself will be executed to define the test.

However, there's an interesting part in the `Benchmark Definition` field:

"[`.match()`](#matches-exec)."

This is a reference to a built-in JavaScript function called `String.prototype.match()`, which attempts to match a string against a regular expression. The notation `"^...\\s*(\\\\S*)"` is a raw regular expression that consists of several parts:

* `^`: matches the start of the string
* `...`: matches any characters (including none) between the caret and the next whitespace character `\s*`
* `(\\\\S*)`: captures one or more non-whitespace characters (`\\S`) in a group (the parentheses imply that this part is capturing its contents)

This regular expression pattern seems to be intended to match some code snippet starting with `java` followed by whitespace and then any sequence of characters.

**Approaches Compared**

There are two approaches compared:

1. **`match()`**: This approach uses the built-in JavaScript function `String.prototype.match()`, which attempts to execute a regular expression on the provided string.
2. **`RegExp.exec()`**: This approach creates a new RegExp object with the same pattern and executes it on the provided string using the `exec()` method.

**Pros and Cons**

**`match()`**:

Pros:

* Efficient, as it's a built-in function optimized for performance
* Simple to use, requiring only a single argument (the regular expression pattern)

Cons:

* Can be slow if the pattern is complex or contains a large number of groups
* May not work correctly with all types of input strings

**`RegExp.exec()`**:

Pros:

* More flexible than `match()`, allowing for more control over the execution process
* Suitable for cases where `match()` would fail, such as when there are no matches in the string

Cons:

* Less efficient than `match()`, requiring more CPU resources and potentially slower execution
* Requires additional memory to store the created RegExp object

**Other Considerations**

Both approaches assume that the input string contains a valid JavaScript code snippet starting with `java`. If this assumption is not met, the tests may fail or produce incorrect results.

It's also worth noting that using `RegExp.exec()` instead of `match()` might be useful if you need to modify or extend the execution process, but in this case, it seems like a straightforward comparison between two built-in functions.

**Libraries Used**

There is no library explicitly used in these benchmark definitions. However, some JavaScript implementations might rely on libraries for regular expression functionality (e.g., V8's RegExp engine).

**Special JS Features or Syntax**

There are no special JS features or syntax used in this benchmark. The code snippet being matched contains a standard JavaScript keyword (`java`) followed by whitespace and then any sequence of characters.

**Alternatives**

Other alternatives to `match()` and `RegExp.exec()` for executing regular expressions in JavaScript include:

* `String.prototype.replace()`: While not designed specifically for execution, it can be used with a substitution function that returns a new string (not the original match).
* `Function.call()`: By passing a string containing a regular expression pattern as an argument to the `Function` constructor and then calling it as if it were a function.
* Custom implementation using a loop or recursive approach.

However, these alternatives are generally less efficient and more cumbersome than using built-in functions like `match()` and `RegExp.exec()`.

Related benchmarks:

matches exec (version: 0)

matches exec

Comparing performance of: matches vs exec

Created: one year ago by: Guest

Jump to the latest result

matches

exec

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):