Benchmark: slice vs substr vs substring vs replace

Script Preparation code:

var example = 'there is no spoon'

Tests:

slice
var result = example.slice(5, example.lenght)
substr
var result = example.substr(5, example.lenght)
substring
var result = example.substring(5, example.lenght)
replace
var result = example.replace('there', '')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
substr
substring
replace

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.82 Safari/537.36

Browser/OS: Chrome 89 on Windows

View result in a separate tab

Test name	Executions per second
slice	5497899.0 Ops/sec
substr	5551729.0 Ops/sec
substring	5493809.0 Ops/sec
replace	4758669.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring the performance of different JavaScript methods for string manipulation is crucial in understanding how various browsers and environments optimize these operations.

The provided benchmark compares `slice`, `substr`, and `substring` methods when used with only a start index, as well as the `replace` method. Here's an explanation of each method:

1.  **`slice()`**: Returns a new string that includes all characters from the current position to the end of the string.

*   Pros: More flexible than `substr` or `substring`, allows specifying both start and end indices.
    *   Cons: Creates a new string object, which can be memory-intensive for large strings.
2.  **`substr()`**: Returns a new string that includes all characters from the current position to the specified length.

*   Pros: More efficient than `slice()` because it returns only the requested number of characters, rather than an entire new string.
    *   Cons: Fixed-length slicing can lead to truncation if the requested length exceeds the remaining characters in the string.
3.  **`substring()`**: Returns a new string that includes all characters from the current position to the specified end index.

*   Pros: Similar to `substr`, but allows specifying an end index, which can be useful for cases where you need to slice from both the start and end of the string.
    *   Cons: Can lead to performance issues if used with large strings due to the creation of a new string object.
4.  **`replace()`**: Replaces occurrences of a specified pattern in the original string with another value.

*   Pros: Not a slicing method, but rather a replacement operation that can be more efficient than creating and manipulating individual characters or substrings.
    *   Cons: Requires careful consideration to avoid unexpected replacements or modifications to the original string.

The provided benchmark results show that:

*   `substr` outperforms both `slice()` and `substring()` methods, likely due to its fixed-length slicing approach.
*   The performance of these methods can be influenced by factors such as browser version, platform, and available memory.

Other alternatives for string manipulation in JavaScript include:

*   **Regular expressions**: Useful for complex pattern matching, text extraction, or validation, but often slower than simple string operations due to the overhead of compiling and executing regex patterns.
*   **Array methods**: Such as `slice()`, `concat()`, and `substring()` (when used on arrays), which can be more efficient than individual string manipulation for certain use cases.

To improve performance in JavaScript:

*   Use caching mechanisms, such as memoization or caching libraries, to store frequently accessed values.
*   Leverage browser-specific optimizations, like `String.prototype.slice()` and `String.prototype.replace()`, which can provide better performance on specific platforms.
*   Optimize for memory usage by using techniques like avoiding unnecessary string allocations or using more efficient data structures.
*   Profile your application's performance using tools like Chrome DevTools or Node.js Inspector to identify bottlenecks and areas for improvement.

Related benchmarks:

slice vs substr vs substring vs replace (version: 0)

Compares slice, substr and substring to each other when there is only a start index

Comparing performance of: slice vs substr vs substring vs replace

Created: 3 years ago by: Registered User

Jump to the latest result

slice

substr

substring

replace

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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