Benchmark: ISO Datetime - add microseconds - replace vs slice

Script Preparation code:

var strIn = '2023-12-18T12:30:00Z';
var strOut = '';

Tests:

replace
strOut = strIn.replace('Z', '123Z');
slice
strOut = strIn.slice(0, -1) + '123Z';

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
replace
slice

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.5764.195 Safari/537.36

Browser/OS: Chrome 116 on Linux

View result in a separate tab

Test name	Executions per second
replace	3552517.5 Ops/sec
slice	4461801.0 Ops/sec

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 its test cases.

**Benchmark Definition**

The benchmark measures the performance difference between two approaches to add microseconds to an ISO datetime string:

1. `strOut = strIn.replace('Z', '123Z');`
2. `strOut = strIn.slice(0, -1) + '123Z';`

**Options Compared**

Two options are compared in this benchmark:

A. **`replace()`**: The `replace()` method is used to replace a specified value with another value. In this case, it's used to replace the `'Z'` suffix (indicating UTC time) with `'123Z'`.

B. **`slice()`**: The `slice()` method returns a new string that includes all characters before the specified start index and up to but not including the specified end index. Here, it's used to remove the last character of the original string (`strIn`) and then append `'123Z'` to it.

**Pros and Cons**

1. **`replace()`**
	* Pros:
		+ Simple and straightforward approach.
		+ Fast because it only requires a single operation (string comparison).
	* Cons:
		+ May be slower if the string needs to be parsed or validated before replacement.
2. **`slice()`**
	* Pros:
		+ Can be faster than `replace()` when dealing with long strings, as it avoids parsing and validation overhead.
	* Cons:
		+ Requires more operations (string slicing and concatenation), which may lead to slower performance.

**Library**

Neither of the two approaches uses a library. They are built-in methods of JavaScript's String prototype.

**Special JS Feature or Syntax**

There is no special JavaScript feature or syntax used in this benchmark. The code only employs standard JavaScript methods (`replace()` and `slice()`) and basic string manipulation techniques.

**Other Alternatives**

If the developer wanted to explore alternative approaches, they might consider:

1. **Using a dedicated date formatting library**, such as moment.js or Luxon.
2. **Implementing custom parsing and formatting logic**, potentially using regular expressions or other specialized methods.

However, in this specific benchmark, both `replace()` and `slice()` are used because they are concise, efficient, and straightforward for the task at hand.

**Benchmark Preparation Code**

The script preparation code provided sets up a test string (`strIn`) with an ISO datetime value followed by `'Z'`, which is then modified according to each approach (either replaced or sliced). The resulting strings (`strOut`) are not used to compare performance, but rather serve as input for the `Benchmark Definition` json.

Overall, this benchmark helps users understand the relative performance of two simple string manipulation approaches in JavaScript: replacing a character with another value versus removing a character and appending a new value.

Related benchmarks:

ISO Datetime - add microseconds - replace vs slice (version: 0)

ISO Datetime - add microseconds - replace vs slice

Comparing performance of: replace vs slice

Created: 2 years ago by: Guest

Jump to the latest result

replace

slice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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