Benchmark: Performance Test: substring vs substr vs slice vs replace last character

Script Preparation code:

var string = "I am the god of hellfire, and I bring you...."

Tests:

substring
var substring = string.substring(0, -1);
substr
var substr = string.substr(0, -1);
replace
var replace = string.replace(/.$/g, '');
slice
var slice = string.slice(0, -1);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
substring
substr
replace
slice

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

**Overview**

The provided benchmark, MeasureThat.net, tests the performance of four different JavaScript methods: `substring`, `substr`, `slice`, and `replace`. The goal is to determine which method is the most efficient for removing the last character from a string.

**Test Cases**

Each test case represents a specific method:

1. **`substring`**: This method uses the `substring()` function to create a new string by extracting a portion of the original string.
2. **`substr`**: Similar to `substring`, but this method uses the `substr()` function, which is an older syntax for the same functionality.
3. **`slice`**: This method uses the `slice()` function to create a new string by extracting a portion of the original string, starting from a specified index and returning a fixed number of characters.
4. **`replace`**: Instead of removing the last character, this test case uses the `replace()` function to replace the last character with an empty string (`''`), which effectively removes it.

**Options Compared**

The four methods are compared in terms of their performance, measured by the number of executions per second (ExecutionsPerSecond) on a specific browser and device platform.

**Pros and Cons**

Here's a brief analysis of each method:

* **`substring`**: This method creates a new string by extracting a portion of the original string. While it works well for most cases, it may be slower than other methods because it involves creating a new object.
* **`substr`**: As mentioned earlier, this method uses an older syntax and is likely to be slower than `substring`.
* **`slice`**: This method creates a new string by extracting a portion of the original string. It's similar to `substring`, but with a different indexing approach. While it may be slightly faster than `substring` due to its optimized implementation, it's still creating a new object.
* **`replace`**: Using `replace()` to remove the last character is an interesting approach. While it works well in this specific test case, using `replace()` for general string manipulation can be slower and more memory-intensive than other methods.

**Library: JavaScript String Methods**

None of the libraries are explicitly mentioned in the provided code. However, these string methods are built-in to JavaScript and are implemented by the engine (e.g., V8 for Chrome).

**Special JS Feature or Syntax**

The `substring` method has some special cases:

* When used with two arguments (start, end), it creates a new string containing all characters from start to end.
* When used with one argument (end) and omitted start value, it extracts all characters up to but not including the specified end index.

These cases are not relevant to this specific benchmark, which only tests removing the last character.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.131 Safari/537.36

Browser/OS: Chrome 92 on Windows

View result in a separate tab

Test name	Executions per second
substring	16411004.0 Ops/sec
substr	16739930.0 Ops/sec
replace	7487183.0 Ops/sec
slice	16033281.0 Ops/sec

Related benchmarks:

Performance Test: substring vs substr vs slice vs replace last character (version: 1)

Comparing performance of: substring vs substr vs replace vs slice

Created: 4 years ago by: Registered User

Jump to the latest result

substring

substr

replace

slice

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):