Benchmark: string.at(-1) vs string[string.length-1] vs string.slice(-1)

Tests:

at(-1)
const string = "banana_pie"; string.at(-1);
length-1
const string = "banana_pie"; string[string.length-1];
slice(-1)
const string = "banana_pie"; string.slice(-1);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
at(-1)
length-1
slice(-1)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 127 on Android

View result in a separate tab

Test name	Executions per second
at(-1)	16872882.0 Ops/sec
length-1	29978592.0 Ops/sec
slice(-1)	26858438.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmarked Methods**

The three methods being benchmarked are used to extract the last character from a string:

1. `string.at(-1)`: This method uses the `at()` function, which returns the nth property of an object or array, or undefined if the index is out of range. In this case, it's used with a negative index `-1` to get the last character.
2. `string[string.length-1]`: This method uses string indexing with a calculated value `string.length - 1`, which is equivalent to getting the last character using `at(-1)`.
3. `string.slice(-1)`: This method uses the `slice()` function, which returns a new string containing a subset of characters from an original string. When used with `-1` as the offset, it extracts the last character.

**Comparison**

The benchmark compares the performance of these three methods on different JavaScript engines and browsers:

* `at(-1)` vs `string[string.length-1]`: Both methods are equivalent, but `at(-1)` might be slightly faster due to its more concise syntax.
* `at(-1)` vs `slice(-1)`: The winner depends on the specific browser and engine. However, in general, `at(-1)` is expected to be faster since it's a single property access, whereas `slice()` creates a new string object.

**Pros and Cons**

Here are some pros and cons of each method:

* `string.at(-1)`: Pros:
	+ Concise syntax
	+ Fast execution (due to optimized property access)
	Cons: Not supported in older browsers.
* `string[string.length-1]`: Pros: Widely supported across modern browsers, equivalent to `at(-1)` in terms of performance. Cons: Less concise syntax compared to `at(-1)`.
* `string.slice(-1)`: Pros:
	+ Can be used to extract multiple characters at once (not just the last one).
	+ Supports older browsers that don't support `at()`. Cons:
		- Creates a new string object, which might have performance implications.
		- Less concise syntax compared to `at(-1)`.

**Library**

None of the benchmarked methods rely on external libraries. However, if you're interested in understanding more about the properties used:

* `string.at()`: Introduced in ECMAScript 2019 (ES11), this property allows accessing array-like objects using a numeric index.
* `string.slice()`: This function has been part of JavaScript since its inception and is widely supported across all browsers.

**Special JS Features/Syntax**

The benchmark uses the following special features:

* `at(-1)`: A new property introduced in ECMAScript 2019 (ES11), allowing array-like object access using a negative index.
* `slice(-1)`: Uses the `slice()` function, which is widely supported but might not be as concise or efficient as `at(-1)`.

**Alternatives**

If you're looking for alternative ways to extract the last character from a string, here are some options:

* Using `substr()` method: `string.substr(string.length - 1)`.
* Using regular expressions: `\w` (match any word character, including underscores) followed by `$` (assert end of string).

Keep in mind that these alternatives might not be as efficient or concise as the original methods.

Related benchmarks:

string.at(-1) vs string[string.length-1] vs string.slice(-1) (version: 0)

Some methods to get the last character of a string

Comparing performance of: at(-1) vs length-1 vs slice(-1)

Created: one year ago by: Guest

Jump to the latest result

at(-1)

length-1

slice(-1)

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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