Benchmark: string split vs substring vs substr (first item)

string split vs substring vs substr (first item) (version: 0)

The first item of a string, by separator (The header from a JWT/JWS)

Comparing performance of: substring with indexOf vs substr with indexOf vs string.split with limit (array index) vs string.split with limit (destructuring) vs string.split without limit (destructuring) vs string.split without limit (array index)

Created: 3 years ago by: Guest

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Tests:

substring with indexOf
const jwt = `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c` const header = jwt.substring(0,jwt.indexOf('.'))
substr with indexOf
const jwt = `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c` const header = jwt.substr(0,jwt.indexOf('.'))
string.split with limit (array index)
const jwt = `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c` const header = jwt.split('.',1)[0]
string.split with limit (destructuring)
const jwt = `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c` const [header] = jwt.split('.',1)
string.split without limit (destructuring)
const jwt = `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c` const [header] = jwt.split('.')
string.split without limit (array index)
const jwt = `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c` const header = jwt.split('.')[0]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
substring with indexOf
substr with indexOf
string.split with limit (array index)
string.split with limit (destructuring)
string.split without limit (destructuring)
string.split without limit (array index)

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided benchmark measures the performance of three ways to extract the first item from a string: `substring` and `substr` methods, both using indexing, and two `string.split` approaches using array destructuring or index-based extraction.

**Test Cases**

Each test case creates a JSON Web Token (JWT) string with a header, payload, and signature. The goal is to extract the first item from the header part of the JWT.

1. **Substring with IndexOf**: Uses the `substring` method with indexing (`indexOf`) to extract the first item.
2. **Substr with IndexOf**: Similar to the previous test, but uses the `substr` method instead of `substring`.
3. **String.Split without Limit (Array Index)**: Uses the `split` method with an array index to extract the first item from the header part of the JWT.
4. **String.Split without Limit (Destructuring)**: Same as the previous test, but uses destructuring assignment to extract the first item from the header part of the JWT.
5. **String.Split with Limit (Array Index)**: Uses the `split` method with an array index, similar to the previous test, but with a limit on the number of splits.
6. **String.Split with Limit (Destructuring)**: Similar to the previous test, but uses destructuring assignment with a limit on the number of splits.

**Benchmarks**

The latest benchmark results show that:

* `substring` and `substr` methods using indexing are the slowest,
* `string.split` approaches without limits are faster than those with limits,
* Destructuring assignment is generally faster than array index-based extraction.

**Conclusion**

The test results suggest that for this specific use case, destructuring assignment is the fastest way to extract the first item from a string. However, it's essential to note that the performance differences between these methods may vary depending on the specific requirements and constraints of your application.

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