Benchmark: javascript replaceAt

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

// Set up
const replaceAt = (str, index, character) => str.substr(0, index) + character + str.substr(index+character.length);

const replaceAt2 = (str, index, character) => {
    const chars = Array.from(str);
    
    chars[index] = character;
    return chars.join('');
}

const replaceAt3 = (str, index, character) => {
    const chars = str.split('');
    
    chars[index] = character;
    return chars.join('');
}

// Set up test variables

const str = new Array(10000).fill('0123456789').join('0123456789');

Tests:

Substr
replaceAt(str, str.length / 2, "W");
Array.from
replaceAt2(str, str.length / 2, "W");
Array.split
replaceAt3(str, str.length / 2, "W");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Substr
Array.from
Array.split

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36

Browser/OS: Chrome 123 on Windows

View result in a separate tab

Test name	Executions per second
Substr	29616630.0 Ops/sec
Array.from	110.0 Ops/sec
Array.split	116.7 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 3 months ago):

LLMs can make mistakes. Check important info.

The benchmark provided tests three different implementations of the `replaceAt` function, which aims to replace a character at a specified index in a string. The variations in the approach utilize different methods to manipulate the string, resulting in performance differences. Each approach is encapsulated in its own function, which is then measured based on how many operations can be executed per second.

### Implementations Compared

1. **Substr Method (`replaceAt`)**:
   ```javascript
   const replaceAt = (str, index, character) => 
       str.substr(0, index) + character + str.substr(index + character.length);
   ```
   - **Description**: This method splits the string into two substrings: one before the specified index and one after the index where the character is to be inserted. It then concatenates the two substrings with the new character in between.
   - **Pros**: Simple and direct method of replacement without creating arrays.
   - **Cons**: The use of `substr` (which is generally more legacy) may not be as optimized as other methods in modern JavaScript engines, especially for larger strings.

2. **Array.from Method (`replaceAt2`)**:
   ```javascript
   const replaceAt2 = (str, index, character) => {
       const chars = Array.from(str);
       chars[index] = character;
       return chars.join('');
   }
   ```
   - **Description**: Here, the string is converted to an array of characters using `Array.from()`, the specified index is updated, and then the array is joined back into a string.
   - **Pros**: This method is potentially easier to read and leverage array functionality, like mutability.
   - **Cons**: Converting a string to an array and back again involves additional overhead, meaning it can be slower than simpler string manipulation techniques—especially for large strings.

3. **Array.split Method (`replaceAt3`)**:
   ```javascript
   const replaceAt3 = (str, index, character) => {
       const chars = str.split('');
       chars[index] = character;
       return chars.join('');
   }
   ```
   - **Description**: Similar to `replaceAt2`, but this method utilizes `split('')` to create the character array from the string. It replaces the character and joins the array back into a string.
   - **Pros**: It is straightforward and allows array mutability.
   - **Cons**: Like the `Array.from` method, converting a string to an array and then back again incurs more processing time, which can negatively impact performance, especially with larger datasets.

### Benchmark Results Overview

The benchmark results indicate the number of function executions per second for each implementation:

- **Substr**: 17,548,484 executions per second - demonstrates this method's high efficiency in replacing characters directly within the string.
- **Array.split**: 147.54 executions per second - shows a significant drop in performance due to the overhead of array manipulation.
- **Array.from**: 137.38 executions per second - similar to `Array.split`, it exhibits inferior performance compared to the direct string manipulation method.

### Considerations

- **Performance**: Efficiency is key when dealing with string manipulations, especially in applications that require high-performance and scalable solutions. The `replaceAt` method using `substr` significantly outperforms the others in this case.
- **Readability vs. Performance**: While `Array.from` and `Array.split` may offer clearer semantics or allow for more complex manipulations, they come at the cost of performance.

### Alternatives

- **Template Literal & Functional Libraries**: In scenarios where readability and chaining operations are favored, using libraries like Lodash or functional programming principles can be beneficial. However, these may also incur extra overhead.
- **Native Methods**: For pure performance-critical applications, optimizing direct manipulations and avoiding conversions (like array operations) is recommended.

In summary, this benchmark effectively illustrates the trade-offs between string manipulation methods in JavaScript, presenting an insightful comparison that highlights how different coding styles can impact performance.

Related benchmarks:

javascript replaceAt (version: 2)

Comparing performance of: Substr vs Array.from vs Array.split

Created: 3 months ago by: Registered User

Jump to the latest result

Substr

Array.from

Array.split

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 3 months ago):