Benchmark: Performance Test: substring vs substr vs slice (remove last char)

Script Preparation code:

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

Tests:

slice
var substring = string.slice(0, -1);
substring
var substring = string.substring(0, string.length - 1);
substr
var substring = string.substr(0, string.length - 1);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
substring
substr

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
slice	20907486.0 Ops/sec
substring	11354052.0 Ops/sec
substr	11306389.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Overview**

The test measures the performance difference between three ways to remove the last character from a string: `slice`, `substring`, and `substr`. The goal is to determine which approach is the fastest.

**Options Compared**

1. **Slice**: The `slice()` method returns a new string, containing all characters from the start index (0) up to, but not including, the end index (which defaults to the end of the string). By using `-1` as the end index, we effectively remove the last character.
2. **Substring**: The `substring()` method also returns a new string, containing all characters from the start index (0) up to, but not including, the end index (which defaults to the length of the original string).
3. **Substr**: The `substr()` method returns a new string, containing all characters from the start index (0) up to, but not including, the end index (which defaults to 1). Again, by using `-1` as the end index, we remove the last character.

**Pros and Cons of Each Approach**

* **Slice**: Pros:
	+ Generally faster than `substring` and `substr`.
	+ Returns a new string, which can be beneficial if you need to work with multiple strings.
*   Cons:
    *   Creates an additional object in memory, which can be a concern for very large datasets.
*   **Substring**: Pros:
    + Can be more efficient than `slice` when the original string is very long and there's no performance penalty from creating an intermediate result.
    + Still creates an additional object in memory.
*   Cons:
    *   Slower than `slice`.
*   **Substr**: Pros:
    + Even slower than `substring`.
    + Can be problematic if you're working with strings that don't have enough characters to reach the default end index of 1.

**Library Used**

None. The benchmark only uses JavaScript's built-in methods and variables.

**Special JS Features or Syntax**

There are no special features or syntax used in this benchmark. The code is straightforward and simple, making it easy to understand for anyone familiar with basic JavaScript programming.

**Other Alternatives**

If you wanted to remove the last character from a string without using any of these three methods, you could use:

*   `string.slice(0, -1)` (same as `slice`)
*   `string.substring(0, string.length - 1)` (same as `substring`)
*   `string.substr(0, string.length - 1)` (same as `substr`)

However, these alternatives do not provide any performance benefits over the original three methods.

I hope this explanation helps you understand what's going on in this benchmark!

Related benchmarks:

Performance Test: substring vs substr vs slice (remove last char) (version: 0)

Comparing performance of: slice vs substring vs substr

Created: 5 years ago by: Guest

Jump to the latest result

slice

substring

substr

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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