Benchmark: slice vs substr vs substring (with end index) -x

Script Preparation code:

var example = '49797516513c2429abcd312a9a5a2e9bf1bf52d9ae93d6389bad60c423f9eff00d1b793a49393050750f9aca023208313ad0fda00d6f22a70379d0cb275a5a77c05887a6f4b38d20c856e18dbd8a1b1565809'

Tests:

slice
var result = example.slice(50,8)
substr
var result = example.substr(50,8)
substring
var result = example.substring(50,8)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
substr
substring

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and its results.

**What is being tested?**

The provided JSON represents a JavaScript microbenchmark that compares the performance of three string manipulation methods: `slice`, `substr`, and `substring`. The test specifically focuses on using only the start index, without specifying an end index. This means that each method will be used to extract a substring from the original string, starting at index 50 and ending at index 8.

**Options compared**

The three options being compared are:

1. **`slice(start, end)`**: This method returns a shallow copy of a portion of an array (or string in this case) specified by its start and end indices.
2. **`substr(start, length)`**: This method returns the substring from the original string starting at the specified index and returning the specified number of characters.
3. **`substring(start, end)`**: This method returns a new string that is a subset of an existing string, without creating a new array (unlike `slice()`).

**Pros and Cons of each approach**

1. **`slice()`**:
	* Pros: Returns a shallow copy of the substring, which can be beneficial for certain use cases.
	* Cons: May incur additional overhead due to the creation of a new string object.
2. **`substr()`**:
	* Pros: Returns the exact substring requested, without creating intermediate objects.
	* Cons: The `length` parameter can lead to performance issues if it's large or if the original string is short.
3. **`substring()`**:
	* Pros: Provides a flexible way to extract substrings and has better performance than `substr()` for larger lengths.
	* Cons: Can create intermediate objects, which may be detrimental in some cases.

**Library usage**

There is no explicit library mentioned in the benchmark definition or test case. However, JavaScript engines like SpiderMonkey (used by Firefox) provide optimized implementations of these methods that may differ from pure JavaScript implementations.

**Special JS features/syntax**

None are explicitly used in this benchmark.

**Other considerations**

* The benchmark uses a fixed string (`example`) to test each method's performance.
* The start index is set to 50, and the end index varies between 8 for `slice()` and `substring()`, and 8 for `substr()`. This may lead to biased results if the engine optimizes for specific indices.

**Alternatives**

Some alternative string manipulation methods in JavaScript include:

1. **`String.prototype.slice.call()`**: A method that calls `slice()` on a string, using it as an array.
2. **`String.prototype.substring.call()`**: A method that calls `substring()` on a string, using it as an array.
3. **`String.prototype.substr.call()`**: A method that calls `substr()` on a string, using it as an array.

Keep in mind that these alternatives may have different performance characteristics and use cases compared to the methods tested in this benchmark.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:70.0) Gecko/20100101 Firefox/70.0

Browser/OS: Firefox 70 on Windows

View result in a separate tab

Test name	Executions per second
slice	204915024.0 Ops/sec
substr	250376976.0 Ops/sec
substring	119228792.0 Ops/sec

Related benchmarks:

slice vs substr vs substring (with end index) -x (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

Created: 5 years ago by: Guest

Jump to the latest result

slice

substr

substring

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):