Benchmark: Replace vs Substring vs Slice at the start with a predefined known string

Script Preparation code:

var prefix = 'test_';
var prefixRegex = /^test_/;
var strIn = 'test_string_data'
var strOut = '';

Tests:

Replace
strOut = strIn.replace(prefixRegex, '');
Substring
strOut = strIn.substring(prefix.length)
Slice
strOut = strIn.slice(prefix.length)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Replace
Substring
Slice

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36

Browser/OS: Chrome 127 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Replace	6640193.0 Ops/sec
Substring	8046834.0 Ops/sec
Slice	8011423.0 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 provided JSON represents a JavaScript benchmark that tests three different approaches to remove a predefined prefix from a string: `replace`, `substring`, and `slice`. The benchmark is designed to measure the performance of these approaches on various browsers, devices, and operating systems.

**Options Compared**

The three options compared are:

1. **`strOut = strIn.replace(prefixRegex, '');`**: This approach uses the `replace()` method with a regular expression to remove the prefix from the input string.
2. **`strOut = strIn.substring(prefix.length)`**: This approach uses the `substring()` method to extract a portion of the input string starting from the length of the prefix.
3. **`strOut = strIn.slice(prefix.length)`**: This approach uses the `slice()` method to extract a portion of the input string starting from the length of the prefix.

**Pros and Cons**

Here's a brief analysis of each approach:

*   **`replace()`**:
    *   Pros: Simple, efficient, and widely supported.
    *   Cons: Can be slower than other approaches for very large strings due to the overhead of regular expressions. May not be suitable for older browsers or environments with limited regex support.
*   **`substring()`**:
    *   Pros: Fast, simple, and works well on most modern browsers. However, it may return an empty string if the prefix is longer than the input string.
*   **`slice()`**:
    *   Pros: Similar performance to `substring()`, with the added benefit of being more flexible and allowing for negative values (e.g., `-3` for 3 characters from the end).
*   **Library Usage**
    The `replace()` method uses a regular expression (`prefixRegex`) to match the prefix. This is a standard JavaScript feature, widely supported across browsers.

**Special JS Features or Syntax**

There's no explicit use of special JavaScript features or syntax in this benchmark.

**Other Considerations**

When evaluating performance, consider factors such as:

*   **String size**: Larger strings may slow down certain approaches.
*   **Browser and environment variations**: Results might differ significantly across different browsers, devices, and operating systems due to varying optimizations, caching, and memory management.
*   **Cache performance**: Some approaches (e.g., `replace()`) may rely on caching, which can impact performance.

**Alternatives**

Other alternatives for removing prefixes from strings include:

*   **Using a library or function**: Consider using libraries like Lodash or custom functions optimized for specific use cases.
*   **Using other string manipulation methods**: Explore other methods like `indexOf()`, `lastIndexOf()`, and `split()`.

The benchmark's design allows users to compare the performance of these three approaches, providing insights into the trade-offs between simplicity, speed, and flexibility.

Related benchmarks:

Replace vs Substring vs Slice at the start with a predefined known string (version: 0)

Comparing performance of: Replace vs Substring vs Slice

Created: one year ago by: Guest

Jump to the latest result

Replace

Substring

Slice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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