Benchmark: replace vs regex replace

Script Preparation code:

var chars = 'abcdefghijklmnopqrstuvwxyz';
var str = '';
for (var i = 0; i < 64; ++i) { str += chars.charAt(Math.floor(Math.random() * chars.length)); }
var pos = Math.floor(Math.random() * str.length);
str = str.substr(0, pos) + '{{tag}}' + str.substr(pos);
var longstr = '';
for (var i = 0; i < 10 * 1024 * 1024; ++i) { str += chars.charAt(Math.floor(Math.random() * chars.length)); }

Tests:

replace
str.replace('{{tag}}', longstr)
regex replace
str.replace(/{{(\w[\.\w]*)}}/g, (match, arg) => { return longstr; })

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
replace
regex replace

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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 and explain what is being tested.

**Benchmark Definition**

The benchmark is designed to compare two approaches for replacing a substring in a string: using the `replace()` method with a regular expression (regex) or by simply passing the replacement string as an argument. The input string, `str`, is generated randomly and contains 64 random characters followed by the tag `{{tag}}` at a random position.

**Options Compared**

The two options being compared are:

1. **`replace()` method with regex**: This approach uses the `replace()` method with a regex pattern to replace the substring. The regex pattern in this case is `/{{(\\w[\\.\\w]*)}}/g`, which matches any sequence of word characters (letters, numbers, and underscores) that includes dot (`.`) or hyphen (`-`) followed by zero or more word characters. The `g` flag at the end makes the replacement global, meaning all occurrences are replaced.
2. **Simple string concatenation**: This approach passes the replacement string as an argument to the `replace()` method without using regex.

**Pros and Cons**

1. **`replace()` method with regex**:
	* Pros: more flexible and powerful than simple string concatenation, can handle complex replacements.
	* Cons: slower and more CPU-intensive due to the overhead of compiling and executing the regex pattern.
2. **Simple string concatenation**:
	+ Pros: faster and less CPU-intensive, since it doesn't require compiling or executing a regex pattern.
	+ Cons: limited flexibility and power compared to using regex.

**Library Used**

The `replace()` method with regex uses JavaScript's built-in regular expression engine.

**Special JS Feature or Syntax**

The benchmark is using the `g` flag in the regex pattern, which is a special feature of modern JavaScript's regular expression engine. This flag makes the replacement global, meaning all occurrences are replaced.

**Other Alternatives**

If you wanted to compare other approaches for replacing a substring, some alternatives could be:

* Using `String.prototype.replace()` with a callback function instead of regex.
* Using a library like jQuery or Lodash that provides its own string manipulation functions.
* Implementing a custom string replacement algorithm using bitwise operations or other low-level techniques.

However, since the benchmark is specifically comparing two approaches for replacing a substring, these alternatives might not be relevant to the analysis.

Related benchmarks:

replace vs regex replace (version: 0)

Comparing performance of: replace vs regex replace

Created: 4 years ago by: Guest

Jump to the latest result

replace

regex 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):