Benchmark: slice vs substr vs substring vs index

Script Preparation code:

var example = 'there is no spoon'

Tests:

slice
var result = example.slice(10,2) ==='o '
substr
var result = example.substr(10,2) === 'o '
substring
var result = example.substring(10,12) === 'o '
index
var result1 = (example[10] === 'o') && (example[11] === ' ')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
substr
substring
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):

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Let's break down the provided benchmark and explain what is being tested, compared, and their pros and cons.

**Benchmark Overview**

The benchmark compares the performance of four different approaches to extract a substring from a given string:

1. `slice(startIndex, endIndex)`
2. `substr(startIndex, endIndex)`
3. `substring(startIndex, endIndex)`
4. Accessing individual characters at the specified index (`example[10] === 'o'`)

**Approaches Compared**

* **Slice**: The `slice()` method creates a new string by extracting a subset of characters from the original string.
* **Substr**: The `substr()` method is similar to `slice()`, but it's older and has some differences in behavior (e.g., it returns `undefined` if the end index is beyond the length of the string).
* **Substring**: The `substring()` method is similar to `slice()` and `substr()`, but it throws an error if the end index is less than the start index.
* **Index Access**: This approach uses direct array access (`example[10] === 'o'`) to extract a single character.

**Pros and Cons**

1. **Slice**: Pros:
	* Efficient, as it creates a new string with the desired characters.
	* Can handle large strings without significant performance degradation.
2. **Substr**: Pros:
	+ Older method, which might be preferred for compatibility reasons.
	+ Some browsers still support it.
	Cons:
	+ Returns `undefined` if the end index exceeds the length of the string.
	+ Less efficient than `slice()` due to the unnecessary creation of a new string.
3. **Substring**: Pros:
	+ Throwing an error if the end index is less than the start index ensures better safety and predictability.
	Cons:
	+ Throws an error, which can be unexpected behavior in some cases.
4. **Index Access**: Pros:
	+ Fast and efficient for single character extraction.
	+ Does not create new strings or objects.
Cons:
	+ Requires direct array access, which might be less readable and maintainable.

**Library Usage**

None of the test cases use any libraries explicitly. However, it's worth noting that these methods are part of the ECMAScript standard, which is implemented by most JavaScript engines.

**Special JS Features/Syntax**

The benchmark does not use any special JavaScript features or syntax beyond what's required to implement the different approaches.

**Alternatives**

Other alternatives to compare in this benchmark could include:

* Using `indexOf()` and concatenation to extract a substring.
* Implementing a custom, optimized string extraction function using bitwise operations or other low-level techniques.
* Comparing the performance of these methods with others that use native libraries (e.g., Python's `str` slicing) or other programming languages.

Keep in mind that the focus of this benchmark is on comparing the performance and behavior of these four specific approaches, rather than exploring alternative methods.

Related benchmarks:

slice vs substr vs substring vs index (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 index

Created: 5 years ago by: Registered User

Jump to the latest result

slice

substr

substring

index

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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