Benchmark: slice vs substring vs [] vs charAt vs charCodeAt

HTML Preparation code:

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

Script Preparation code:

const string = 'some code'

Tests:

slice
string.slice(0,1) === 'so'
substring
string.substring(0,1) == 'so'
[]
string[0] === 's' && string[1] === 'o'
charAt
string.charAt(0) === 's' && string.charAt(1) === 'o'
charCodeAt
string.charCodeAt(0) === 115 && string.charCodeAt(1) === 111

Historical Performance Data aggregated from 8 community runs

Desktop Results:

Chrome 8 runs

substring

150.9M/s

charCodeAt

147.8M/s

[]

146.9M/s

charAt

139.7M/s

slice

124.5M/s

Fastest: substring (1.2x faster)

View exact numbers

✓ substring: 150,881,088 ops/sec
• charCodeAt: 147,799,072 ops/sec
• []: 146,852,864 ops/sec
• charAt: 139,736,896 ops/sec
• slice: 124,536,176 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
substring
[]
charAt
charCodeAt

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/146.0.0.0 Safari/537.36 Edg/146.0.0.0

Browser/OS: Chrome 146 on Windows

View result in a separate tab

charAt

137.2M/s

charCodeAt

127.1M/s

slice

120.9M/s

substring

115.2M/s

[]

112.2M/s

View exact numbers

Test name	Executions per second
✓ charAt	137,195,088 Ops/sec
charCodeAt	127,126,464 Ops/sec
slice	120,907,600 Ops/sec
substring	115,170,336 Ops/sec
[]	112,234,440 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON examines the performance of various methods for accessing characters in a string in JavaScript. The specific methods compared are `slice`, `substring`, array notation (using square brackets), `charAt`, and `charCodeAt`. Each of these methods is evaluated based on how efficiently they can retrieve characters from a given string, which is initialized as `'some code'`.

### Options Compared:

1. **`string.slice(startIndex, endIndex)`**
   - This method returns a section of a string from `startIndex` to `endIndex`. In this test, it checks the first two characters.
   - **Pros**: Flexible; can handle negative indices and return parts of a string easily.
   - **Cons**: Slightly more overhead due to the need to specify two indices.

2. **`string.substring(startIndex, endIndex)`**
   - Similar to `slice`, but it doesn't accept negative indices.
   - **Pros**: Simple for retrieving substrings; intuitive for new developers.
   - **Cons**: May have a performance overhead similar to `slice`, without supporting negative indices.

3. **`string[index]`**
   - Array-like notation to access a character at a specified index directly.
   - **Pros**: Fastest for accessing single characters; clear and concise syntax.
   - **Cons**: Limited to accessing one character at a time; it does not provide substring functionality.

4. **`string.charAt(index)`**
   - Returns the character at the specified index in the string.
   - **Pros**: Semantically clear for character access; handles out-of-bounds indices by returning an empty string.
   - **Cons**: Slightly less performant compared to direct array access notation.

5. **`string.charCodeAt(index)`**
   - Returns the Unicode value of the character at the specified index.
   - **Pros**: Useful when the numeric value of the character is needed; efficient for this operation.
   - **Cons**: Not directly usable for retrieving the character itself; requires additional processing if the character is needed.

### Results Overview

From the benchmark results, `charCodeAt` is the fastest method, achieving approximately 64.2 million executions per second, followed closely by `slice` and `substring`, with around 58.5 and 58.1 million respectively. Array notation `[]` is slightly slower, and `charAt` is the slowest of the options tested.

### Considerations and Alternatives

1. **Performance Context**: 
   - It's important to note that while some methods perform significantly better, the choice of method may depend on the specific use case. If one needs to extract multiple characters or substrings regularly, `slice` or `substring` may still be preferable for code clarity and maintainability.

2. **Alternatives**:
   - For more complex string manipulations, one might consider using libraries like **Lodash** or **underscore.js**, which provide a wide range of utility functions for string manipulation and performance optimizations. However, these libraries introduce additional overhead compared to native methods.

3. **Edge Cases**: 
   - Developers should also consider edge cases (e.g., empty strings, out-of-bounds indices) as performance can vary in accordance with how these methods handle such scenarios.

In summary, each method is optimized for different use cases. While performance is an essential factor, style, clarity, and the specific requirements of the project should guide the choice of which string-access method to implement.

slice vs substring vs [] vs charAt vs charCodeAt (version: 1)

Comparing performance of: `slice vs substring vs [] vs charAt vs charCodeAt`

Created: one year ago by: Registered User

Go to the latest result

slice

substring

[]

charAt

charCodeAt

Historical Performance Data aggregated from 8 community runs

Desktop Results:

Chrome 8 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

slice vs substring vs [] vs charAt vs charCodeAt (version: 1)

Comparing performance of: slice vs substring vs [] vs charAt vs charCodeAt

Created: one year ago by: Registered User

Go to the latest result

slice

substring

[]

charAt

charCodeAt

Historical Performance Data aggregated from 8 community runs

Desktop Results:

Chrome 8 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

Related benchmarks

Comparing performance of: `slice vs substring vs [] vs charAt vs charCodeAt`