Benchmark: Look arounds vs full replace

Script Preparation code:

window.text = '*|firstname|* *|lastname|*';

Tests:

Look Arounds
window.text.replace(/(?<=\*\|)lastname(?=\|\*)/g, 'attendee_lastname');
Full Replace
window.text.replace(/\*\|lastname\|\*/g, '{{attendee_lastname}}');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Look Arounds
Full Replace

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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Let's break down the provided benchmark definition and test cases.

**Benchmark Definition**

The benchmark definition is in JSON format, which defines two different approaches to replace text patterns in a string:

```json
{
  "Name": "Look arounds vs full replace",
  "Description": null,
  "Script Preparation Code": "window.text = '*|firstname|* *|lastname|*';",
  "Html Preparation Code": null
}
```

The script preparation code sets the initial `window.text` variable to a string containing placeholders for first name and last name. This is done to prepare the input data for the test cases.

**Test Cases**

There are two individual test cases:

```json
[
  {
    "Benchmark Definition": "window.text.replace(/(?<=\\*\\|)lastname(?=\\|\\*)/g, 'attendee_lastname');",
    "Test Name": "Look Arounds"
  },
  {
    "Benchmark Definition": "window.text.replace(/\\*\\|lastname\\|\\*/g, '{{attendee_lastname}}');",
    "Test Name": "Full Replace"
  }
]
```

**Options Compared**

The two test cases compare the performance of two different regular expression replacement approaches:

1. **Look Arounds**: This approach uses a positive lookbehind assertion (`(?<=...)`) to ensure that the replacement only happens when the preceding character is exactly `|`. The replacement string `'attendee_lastname'` is replaced in place, without leaving any extra characters.
2. **Full Replace**: This approach uses a full regular expression match (`\\*\\|lastname\\|\\*/g`) with a replacement string `{{attendee_lastname}}`. The resulting string contains placeholders for the replaced text.

**Pros and Cons**

1. **Look Arounds**:
	* Pros: More precise control over the replacement, reduces chance of incorrect replacements.
	* Cons: May be slower due to the added complexity of the lookbehind assertion.
2. **Full Replace**:
	* Pros: Faster execution since it only requires a single regular expression match.
	* Cons: Less precise control over the replacement, increases risk of incorrect replacements.

Other considerations:

* The use of raw strings (`\\`) in both test cases ensures that backslashes are treated as literal characters, rather than escape characters.
* The presence of `g` flags at the end of each regular expression indicates that the replacement should be done globally (i.e., all occurrences in the string).

**Library Usage**

There is no explicit mention of any libraries being used in these test cases. However, it's likely that JavaScript engines like V8 (used by Chrome) and SpiderMonkey (used by Firefox) provide built-in support for regular expression operations.

**Special JS Feature/Syntax**

Neither of the test cases uses any special JavaScript features or syntax beyond standard regular expressions and string manipulation.

**Alternatives**

To compare these two approaches, you could also consider using:

* **String.prototype.replace()**: This method is a standard JavaScript method for replacing strings, which might be a baseline comparison.
* **RegEx.test()**: This method tests whether the entire regular expression pattern matches the entire string, without performing a replacement.
* **Other replacement methods**: Depending on the specific requirements of your benchmark, you could also consider using other replacement methods, such as `String.prototype.replace()` with a custom callback function or a library like regex-ast for more complex replacements.

By considering these alternatives and comparing their performance, you can gain a better understanding of the trade-offs involved in choosing one approach over another.

Related benchmarks:

Look arounds vs full replace (version: 0)

Comparing performance of: Look Arounds vs Full Replace

Created: 3 years ago by: Guest

Jump to the latest result

Look Arounds

Full Replace

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):