Benchmark: small string split + join vs replace regex

Script Preparation code:

var str = 'this is it';

Tests:

regex
str.replace(/./g, "$&Z");
split+join
str.split('').join('Z') + 'Z';

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regex
split+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):

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I'll break down the provided JSON and explain what's being tested, the options compared, pros and cons of each approach, and other considerations.

**Benchmark Description**

The benchmark compares two approaches for splitting a string and then joining it back together:

1. Using the `replace()` method with a regular expression (`str.replace(/./g, \"$&Z\");`).
2. Manually splitting the string into an array, joining each element with the character 'Z', and appending another 'Z' to the end (`str.split('').join('Z') + 'Z';`).

**Options Compared**

The two options being compared are:

1. **Regex Replacement**: Using the `replace()` method with a regular expression to replace each character with itself followed by 'Z'.
2. **Manual Split and Join**: Manually splitting the string into an array, joining each element with the character 'Z', and appending another 'Z' to the end.

**Pros and Cons of Each Approach**

**Regex Replacement:**

Pros:

* Can be more efficient for large strings since it only requires a single pass through the string.
* Can be easily adapted to perform additional operations on each matched substring.

Cons:

* May be slower than manual approaches for small strings due to the overhead of parsing regular expressions.
* Regular expressions can be complex and difficult to read/maintain, especially for non-trivial patterns.

**Manual Split and Join:**

Pros:

* Typically faster for small strings since it avoids the overhead of parsing regular expressions.
* Can be more readable and maintainable, especially for simple cases.

Cons:

* Requires manual iteration over each character in the string.
* May not be as efficient for large strings due to the need to create an array of substrings.

**Other Considerations**

The benchmark does not consider other approaches, such as using `substring()` or `slice()`, which might offer alternative solutions depending on the specific use case.

**Library Usage**

In this benchmark, no external libraries are used. However, it's worth noting that some JavaScript engines (e.g., V8) provide built-in support for regular expressions and string manipulation through APIs like `String.prototype.replace()` or `String.prototype.split()`.

If you're interested in exploring alternative approaches, here are a few examples:

* Using `substring()` or `slice()` to create an array of substrings.
* Employing custom loop-based solutions using `charCodeAt()`, `charAt()`, and `concat()`.
* Leveraging modern JavaScript features like `iterable` methods (e.g., `String.prototype.entries()`) for improved performance.

Keep in mind that the choice of approach depends on the specific requirements of your project, such as speed, readability, or maintainability.

Related benchmarks:

small string split + join vs replace regex (version: 0)

Comparing performance of: regex vs split+join

Created: 2 years ago by: Guest

Jump to the latest result

regex

split+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):