Benchmark: Regex vs split/join 37123123123

Script Preparation code:

var str = 'Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxyAbcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy';
var regex = new RegExp(/^(.*)\s*\b(\w+)\W*$/);

Tests:

Regex
regex.exec(str);
Split and Join
foo = str.split(' '); last = foo[foo.length - 1]; result = [foo.slice(0, foo.length - 1).join(' '), last]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Regex
Split and Join

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases to understand what's being tested.

**Benchmark Definition**

The `Script Preparation Code` section of the benchmark definition provides a string `str` that is used as input for both tests. The string contains repeated sequences of characters, which will be split and joined in different ways.

**Test Cases**

There are two test cases:

1. **Regex**: This test uses the `exec()` method to execute a regular expression (`regex`) on the input string `str`. The regular expression `/^(.*)\\s*\\b(\\w+)\\W*$/` matches the first word in the string, ignoring whitespace characters.
2. **Split and Join**: This test splits the input string into words using the `split()` method with a space character as the separator, then takes the last word using indexing (`foo[foo.length - 1]`). Finally, it joins all but the last word back together using the `join()` method.

**Comparison**

The two tests are compared in terms of performance. The test case that runs faster will be reported as having a higher `ExecutionsPerSecond` value.

**Pros and Cons**

**Regex:**

Pros:

* Can handle more complex patterns, such as groups and alternatives.
* May be more efficient for certain types of input data.

Cons:

* Can be slower due to the overhead of compiling and executing regular expressions.
* May not perform well on very large inputs or those with many repeated patterns.

**Split and Join:**

Pros:

* Typically faster than using regular expressions, especially for simple splits like word boundaries.
* More memory-efficient since it only requires creating a single array of words.

Cons:

* Limited to splitting based on whitespace characters or other separators specified in the code.
* May not handle edge cases correctly if the separator is not present.

**Library**

The `exec()` method and regular expressions are part of the JavaScript Standard Library, which provides a set of built-in functions for working with strings. The `split()` and `join()` methods are also standard library functions.

**Special JS Feature or Syntax**

There doesn't appear to be any special JavaScript features or syntax being used in this benchmark that would affect its performance. Both tests use basic JavaScript operations and do not rely on any advanced or experimental features.

**Other Alternatives**

For testing string manipulation benchmarks, other alternatives might include:

* Using a different separator for the split operation (e.g., `split()` with an empty string).
* Adding more complex patterns to the regular expression.
* Increasing the size of the input string or repeating it multiple times to simulate real-world performance scenarios.
* Adding additional processing steps after the split and join operations, such as filtering or sorting.

Keep in mind that these alternatives would depend on the specific requirements and goals of your benchmark.

Related benchmarks:

Regex vs split/join 37123123123 (version: 0)

Comparing performance of: Regex vs Split and Join

Created: 4 years ago by: Guest

Jump to the latest result

Regex

Split and Join

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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