Benchmark: char index vs charAt() for the first character

Script Preparation code:

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

Tests:

character index
if (str[0] == 'b') noop();
charAt()
if (str.charAt(0) == 'b') noop();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
character index
charAt()

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36

Browser/OS: Chrome 87 on Windows

View result in a separate tab

Test name	Executions per second
character index	11662624.0 Ops/sec
charAt()	11709602.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases to understand what is being tested.

**Benchmark Definition:**

The benchmark defines two test cases: "character index" and "charAt()". Both tests aim to measure the performance of accessing the first character of a string using different methods.

**Script Preparation Code:**
```javascript
var str = 'foo bar baz';
var noop = Function.prototype;
```
This code sets up a sample string `str` containing the characters 'f', 'o', 'o', ' ', 'b', 'a', 'r', and 'b', followed by 'a', 'z'. It also creates an empty function object `noop`, which will be used to verify that the benchmarking is working correctly.

**Html Preparation Code:**
The HTML preparation code is empty, indicating that no specific HTML setup is required for this benchmark.

**Test Cases:**

1. **Character Index Test (Test Name: "character index")**

Benchmark Definition:
```javascript
if (str[0] == 'b') noop();
```
This test uses the square bracket notation (`[]`) to access the first character of the string `str`. The condition checks if the first character is equal to `'b'`, and if true, it calls the empty function object `noop`.

2. **charAt() Test (Test Name: "charAt()")**

Benchmark Definition:
```javascript
if (str.charAt(0) == 'b') noop();
```
This test uses the `charAt()` method of the string `str` to access the first character. The condition is similar to the previous test, checking if the first character is equal to `'b'`, and calling `noop` if true.

**Library:**

In both tests, there is no explicit library mentioned or used. However, it's worth noting that JavaScript strings do not have a built-in method for accessing individual characters like in Python or some other languages. The square bracket notation (`[]`) and the `charAt()` method are part of the language's syntax.

**Pros and Cons:**

* **Square Bracket Notation (Character Index Test):**
	+ Pros:
		- Fast and efficient, as it directly accesses the array index.
	+ Cons:
		- May be less readable or intuitive for some developers.
		- Does not provide a clear indication of which character is being accessed.
* **charAt() Method (CharAt() Test):**
	+ Pros:
		- More readable and explicit, as it clearly indicates which character is being accessed.
		- Can be more forgiving if the string is not in the correct format or order.
	+ Cons:
		- May be slower due to the overhead of calling a method.

**Other Considerations:**

* Both tests are designed to measure the performance of accessing individual characters in a string. The benchmark definition and test cases can be modified to compare other string operations, such as concatenation, substring extraction, or regular expression matching.
* To make the benchmark more comprehensive, additional test cases could be added to cover different edge cases, such as:
	+ Empty strings
	+ Strings with non-ASCII characters
	+ Strings with a large number of characters

**Alternatives:**

Other alternatives for measuring string performance in JavaScript include:

1. Using the `String.prototype.slice()` method or `String.prototype.substring()` method to extract substrings.
2. Using regular expressions to search for patterns within strings.
3. Using a library like Lodash or Underscore.js, which provide utility functions for working with strings.

These alternatives can be used to create more comprehensive benchmarks that cover a wider range of string operations and edge cases.

Related benchmarks:

char index vs charAt() for the first character (version: 0)

Compare methods for testing string's last character.

Comparing performance of: character index vs charAt()

Created: 4 years ago by: Guest

Jump to the latest result

character index

charAt()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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