Benchmark: char index vs charAt() vs slice() with Object

Script Preparation code:

var str = new String('foo bar baz');
var noop = Function.prototype;

Tests:

character index
if (str[0] == 'f') noop();
charAt()
if (str.charAt(0) == 'f') noop();
slice()
if (str.slice(0, 1) == 'f') noop();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
character index
charAt()
slice()

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares three methods to access the first character of a string: using square brackets (`[]`), `charAt()`, and `slice()` with an object.

**Methods Comparison**

Here's a brief overview of each method:

1. **Square Brackets (`[]`)**: This is the most common way to access a property of an object in JavaScript, including strings. It works by creating a new object reference that contains the first character of the string and then checking if it matches the expected value.
2. **`charAt()`**: The `charAt()` method returns the character at the specified index of a string. In this case, we're using the first index (0) to get the first character.
3. **`slice()` with an object**: This approach uses the `slice()` method to extract a subset of characters from the string, and then checks if the result matches the expected value.

**Pros and Cons**

Here are some pros and cons for each approach:

1. **Square Brackets (`[]`)**:
	* Pros: Simple, fast, and widely supported.
	* Cons: Creates a new object reference, which can be unnecessary.
2. **`charAt()`**:
	* Pros: Fast and efficient, as it directly accesses the character at the specified index.
	* Cons: May not work in older browsers that don't support `charAt()`.
3. **`slice()` with an object**:
	* Pros: Can provide more flexibility, but may be slower due to the additional operation.
	* Cons: Creates a new string reference, which can be unnecessary.

**Library and Special JS Features**

None of these methods rely on any specific libraries or special JavaScript features beyond what's built into the browser. However, it's worth noting that some older browsers might not support `charAt()` or `slice()` with an object.

**Other Alternatives**

If you wanted to test other approaches, here are a few alternatives:

* Using the `substr()` method instead of `slice()`.
* Using a regular expression (`/./`) to extract the first character.
* Using a function like `String.prototype[0]` (which is equivalent to `str[0]`).

However, these alternatives might not be as common or efficient as the methods being compared in this benchmark.

In summary, this benchmark tests three common ways to access the first character of a string: using square brackets (`[]`), `charAt()`, and `slice()` with an object. Each approach has its pros and cons, and the results provide insight into their relative performance.

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36

Browser/OS: Chrome 81 on Mac OS X 10.14.6

View result in a separate tab

Test name	Executions per second
character index	3236445.5 Ops/sec
charAt()	3035965.5 Ops/sec
slice()	2942014.0 Ops/sec

Related benchmarks:

char index vs charAt() vs slice() with Object (version: 0)

Compare methods for testing string's beggining character.

Comparing performance of: character index vs charAt() vs slice()

Created: 4 years ago by: Guest

Jump to the latest result

character index

charAt()

slice()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):