Benchmark: charAt() vs slice()

Script Preparation code:

var str = 'foo bar baz';
var noop = Function.prototype;

Tests:

charAt()
if (str.charAt(str.length - 1) == 'f') noop();
slice()
if (str.slice(-1) == 'f') noop();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
charAt()
slice()

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:123.0) Gecko/20100101 Firefox/123.0

Browser/OS: Firefox 123 on Windows

View result in a separate tab

Test name	Executions per second
charAt()	2327037952.0 Ops/sec
slice()	2328861184.0 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.

**Benchmark Definition:**

The benchmark is comparing two methods for accessing the last character of a string in JavaScript:

1. `str.charAt(str.length - 1)`
2. `str.slice(-1)`

**Options Compared:**

We have two options being compared here:

* **Method 1: charAt()**
	+ This method takes an index as an argument and returns the character at that position.
	+ In this case, we're passing `str.length - 1` as the index to access the last character of the string.
* **Method 2: slice()**
	+ This method creates a new string by extracting a section from another string.
	+ By passing `-1` as the offset, we're effectively extracting the last character of the original string.

**Pros and Cons:**

Both methods have their trade-offs:

* **charAt():**
	+ Pros:
		- Directly accesses the last character without creating a new string.
		- May be faster since it doesn't involve creating a new string.
	+ Cons:
		- Requires passing an index, which can lead to errors if not done correctly.
		- May have additional overhead due to the function call and argument passing.
* **slice():**
	+ Pros:
		- More flexible and intuitive, as it allows extracting any section of a string.
		- Easier to use than charAt() since no explicit index is required.
	+ Cons:
		- Creates a new string, which can be slower and more memory-intensive.
		- May not be optimized for accessing the last character specifically.

**Library:**

There is no external library being used in this benchmark. The `noop()` function is defined locally using the `Function.prototype` syntax to create an empty function that does nothing when called.

**Special JS Feature/Syntax:**

This benchmark doesn't use any special JavaScript features or syntax beyond what's necessary for the test. It's a straightforward comparison of two methods.

**Other Alternatives:**

If we wanted to compare other methods for accessing the last character of a string, some alternatives could include:

* Using `str.substring(str.length - 1)` (similar to slice() but with a different API)
* Using a regular expression (`/./`) to access the last character
* Using `str.split()` followed by indexing into the resulting array

However, these alternatives might not be as straightforward or efficient as charAt() and slice(), which are both part of the standard JavaScript string methods.

Related benchmarks:

charAt() vs slice() (version: 0)

Compare methods for accessing string's last character

Comparing performance of: charAt() vs slice()

Created: 4 years ago by: Guest

Jump to the latest result

charAt()

slice()

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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